Metallic material for electronic components and method for producing same, and connector terminals, connectors and electronic components using same

ABSTRACT

The present invention provides metallic materials for electronic components, having low degree of whisker formation, low adhesive wear property and high durability, and connector terminals, connectors and electronic components using such metallic materials. The metallic material for electronic components includes: a base material; a lower layer formed on the base material, the lower layer being constituted with one or two or more selected from a constituent element group A, namely, the group consisting of Ni, Cr, Mn, Fe, Co and Cu; an intermediate layer formed on the lower layer, the intermediate layer being constituted with one or two or more selected from the constituent element group A and one or two selected from a constituent element group B, namely, the group consisting of Sn and In; and an upper layer formed on the intermediate layer, the upper layer being constituted with one or two selected from the constituent element group B and one or two or more selected from a constituent element group C, namely, the group consisting of Ag, Au, Pt, Pd, Ru, Rh, Os and Ir; wherein the thickness of the lower layer is 0.05 μm or more and less than 5.00 μm; the thickness of the intermediate layer is 0.01 μm or more and less than 0.40 μm; and the thickness of the upper layer is 0.02 μm or more and less than 1.00 μm.

TECHNICAL FIELD

The present invention relates to a metallic material for electroniccomponents and a method for producing the same, and connector terminals,connectors and electronic components using the same.

BACKGROUND ART

In connectors as connecting components for electronic devices forconsumer use and for vehicle use, materials are used in which baseplating of Ni or Cu is applied to the surface of brass or phosphorbronze materials and Sn or Sn alloy plating is further applied to thebase plating. Sn or Sn alloy plating is generally required to haveproperties such as low contact resistance and high solder wettability,and further, recently the reduction of the insertion force has also beenrequired at the time of joining together a male terminal and a femaleterminal molded by press processing of plating materials. In theproduction process, on the plating surface, there occur sometimeswhiskers, which are needle crystals, causing problems such as shortcircuiting, and hence such whiskers are also required to be suppressedsatisfactorily.

In this regard, Patent Literature 1 discloses an electrical contactmaterial including a contact base material, a ground layer composed ofNi or Co, or an alloy of both of Co and Ni and formed on the surface ofthe contact base material, and an Ag—Sn alloy layer formed on thesurface of the ground layer, wherein the average concentration of Sn inthe Ag—Sn alloy layer is less than 10 mass %, and the concentration ofSn in the Ag—Sn alloy layer is varied with a concentration gradient soas to increase from the interface with the ground layer toward thesurface layer portion of the Ag—Sn alloy layer. According to PatentLiterature 1, an electrical contact material excellent in wearresistance, corrosion resistance and processability is described, andthe electrical contact material is described to be able to be producedwith an extremely low cost.

Patent Literature 2 discloses a material for electric/electroniccomponents wherein on the surface of a substrate having a surfacecomposed of Cu or a Cu alloy, through the intermediary of anintermediate layer composed of a Ni layer or a Ni alloy layer, a surfacelayer composed of a Sn layer or a Sn alloy layer is formed, each ofthese layers containing an Ag₃Sn (ε phase) compound and having athickness of 0.5 to 20 μm. As described in Patent Literature 2, anobject of the invention described in Patent Literature 2 is to provide amaterial for electrical/electronic components, wherein the surface layeris lower in melting point than Sn, excellent in solderability, and freefrom the occurrence of whisker; the joint strength of the junctionformed after soldering is high and at the same time the temporaldegradation of the joint strength at high temperatures is hardly caused,and hence the material is suitable for a lead material; even when thematerial is used in a high-temperature environment, the increase of thecontact resistance is suppressed, the material does not cause thedegradation of the connection reliability with the counterpart member,and hence the material is suitable as a contact material, the objectalso including the provision of a method for producing theabove-described material, and the provision of electrical/electroniccomponents using the above-described material.

Patent Literature 3 discloses a covering material including a basematerial having electrically conductive property and a covering layerformed on the base material, wherein the covering layer includes anintermetallic compound of Sn and a precious metal at least on thesurface side thereof. Patent Literature 3 describes an object thereof isto provide a covering material being low in contact resistance, having alow friction coefficient so as to be effective in reduction of insertionforce, being excellent in oxidation resistance and having stableproperties over a long period of time, and a method for producing thecovering material.

CITATION LIST Patent Literature

-   [Patent Literature 1] Japanese Patent Laid-Open No. Hei 4-370613-   [Patent Literature 2] Japanese Patent Laid-Open No. Hei 11-350189-   [Patent Literature 3] Japanese Patent Laid-Open No. 2005-126763

SUMMARY OF INVENTION Technical Problem

However, the technique described in Patent Literature 1 has not revealedthe relation to the recently required reduction of the insertion forceand the relation to the occurrence and nonoccurrence of the whiskers.The average concentration of Sn in the Ag—Sn alloy layer is less than 10mass %, and the proportion of Ag in the Ag—Sn alloy layer isconsiderably large, and hence the gas corrosion resistance against thegases such as chlorine gas, sulfurous acid gas and hydrogen sulfide isnot sufficient according to the evaluation performed by the presentinventors.

In the technique described in Patent Literature 2, a surface layer isinvolved which is formed of a Sn layer or a Sn-alloy layer including anAg₃Sn (ε-phase) compound and having a thickness of 0.5 to 20 μm, andaccording to the evaluation performed by the present inventors, thissurface layer thickness has resulted in the occurrence of areasincapable of sufficiently reducing the insertion force. The content ofthe Ag₃Sn (ε-phase) of the surface layer formed of a Sn layer or aSn-alloy layer is also described to be 0.5 to 5% by mass in terms of Ag,the proportion of Sn in the surface layer formed of a Sn layer or aSn-alloy layer is large, the thickness of the surface layer formed of aSn layer or a Sn-alloy layer, and hence, according to the evaluationperformed by the present inventors, whiskers occurred and the finesliding wear resistance was not sufficient. The heat resistance and thesolder wettability were also not sufficient.

In the technique described in Patent Literature 3, the covering layerincludes an intermetallic compound of Sn and a precious metal, thethickness of the intermetallic compound (Ag₃Sn) of Sn and a preciousmetal is preferably set at 1 μm or more and 3 μm or less, and accordingto the evaluation performed by the present inventors, this thickness wasfound to be unable to sufficiently decrease the insertion force.

As described above, electronic component metallic materials having aconventional Sn—Ag alloy/Ni base plating structure still cannotsufficiently decrease the insertion force and a problem has been leftunsolved in that whiskers occur. For the durability (heat resistance,solder wettability, fine sliding wear resistance and gas corrosionresistance), it is difficult to achieve sufficiently satisfactoryspecifications and such specifications have not yet been clear.

The present invention has been achieved in order to solve theabove-described problems, and an object of the present invention is toprovide metallic materials for electronic components, having low degreeof whisker formation, low adhesive wear property and high durability,and connector terminals, connectors and electronic components using suchmetallic materials. Here, the adhesive wear means the wear phenomenonmade to occur due to the shear, caused by frictional movement, of theadhesive portions constituting the real contact area between solidobjects. With the increase of the adhesive wear, the insertion force isincreased when a male terminal and a female terminal are joinedtogether.

Solution to Problem

The present inventors made a diligent study, and consequently havediscovered that a metallic material for electronic components, havinglow degree of whisker formation, low adhesive wear property and highdurability can be prepared by disposing a lower layer, an intermediatelayer and an upper layer in this order on a base material, usingpredetermined metals for the lower layer, the intermediate layer and theupper layer, respectively, and assigning predetermined thickness valuesand predetermined compositions to the lower, intermediate and upperlayers, respectively.

An aspect of the present invention perfected on the basis of theabove-described discovery is a metallic material for electroniccomponents including: a base material; a lower layer formed on the basematerial, the lower layer being constituted with one or two or moreselected from a constituent element group A, namely, the groupconsisting of Ni, Cr, Mn, Fe, Co and Cu; an intermediate layer formed onthe lower layer, the intermediate layer being constituted with one ortwo or more selected from the constituent element group A and one or twoselected from a constituent element group B, namely, the groupconsisting of Sn and In; and an upper layer formed on the intermediatelayer, the upper layer being constituted with one or two selected fromthe constituent element group B and one or two or more selected from aconstituent element group C, namely, the group constituting of Ag, Au,Pt, Pd, Ru, Rh, Os and Ir; wherein the thickness of the lower layer is0.05 μm or more and less than 5.00 μm; the thickness of the intermediatelayer is 0.01 μm or more and less than 0.40 μm; the thickness of theupper layer is 0.02 μm or more and less than 1.00 μm; and the metallicmaterial for electronic components has low degree of whisker formation,low adhesive wear property and high durability.

In the metallic material for electronic components of the presentinvention in an embodiment, the minimum thickness (μm) of the upperlayer is 50% or more of the thickness (μm) of the upper layer.

In the metallic material for electronic components of the presentinvention in another embodiment, the maximum value (μm) of the elevationdifferences between the adjacent hills and valleys in the profile of theinterface between the upper layer and the intermediate layer is 50% orless of the thickness (μm) of the upper layer.

In the metallic material for electronic components of the presentinvention in yet another embodiment, on the surface of the upper layer,a region where the total atomic concentration (at %) of the constituentelements B≥the total atomic concentration (at %) of the constituentelements C and the atomic concentration (at %) of O≥10 at % is presentin the range of 0.02 μm or less.

In the metallic material for electronic components of the presentinvention in yet another embodiment, the upper layer includes themetal(s) of the constituent element group B in a content of 10 to 50 at%.

In the metallic material for electronic components of the presentinvention in yet another embodiment, in the upper layer, ζ(zeta)-phasebeing a Sn—Ag alloy including Sn in a content of 11.8 to 22.9 at % ispresent.

In the metallic material for electronic components of the presentinvention in yet another embodiment, in the upper layer, anε(epsilon)-phase being Ag₃Sn is present.

In the metallic material for electronic components of the presentinvention in yet another embodiment, in the upper layer, a ζ(zeta)-phasebeing a Sn—Ag alloy including Sn in a content of 11.8 to 22.9 at % andan ε(epsilon)-phase being Ag₃Sn are present.

In the metallic material for electronic components of the presentinvention in yet another embodiment, in the upper layer, only theε(epsilon)-phase being Ag₃Sn is present.

In the metallic material for electronic components of the presentinvention in yet another embodiment, in the upper layer, theε(epsilon)-phase being Ag₃Sn and β-Sn being a Sn single phase arepresent.

In the metallic material for electronic components of the presentinvention in yet another embodiment, in the upper layer, theζ(zeta)-phase being a Sn—Ag alloy including Sn in a content of 11.8 to22.9 at %, the ε(epsilon)-phase being Ag₃Sn and β-Sn being a Sn singlephase are present.

In the metallic material for electronic components of the presentinvention in yet another embodiment, the intermediate layer includes ametal(s) of the constituent element group B in a content of 35 at % ormore.

In the metallic material for electronic components of the presentinvention in yet another embodiment, in the intermediate layer, Ni₃Sn₄and Ni₃Sn₂ are present.

In the metallic material for electronic components of the presentinvention in yet another embodiment, in the intermediate layer, Ni₃Sn₄and β-Sn being a Sn single phase are present.

In the metallic material for electronic components of the presentinvention in yet another embodiment, the thickness ratio between theupper layer and the intermediate layer is such that upperlayer:intermediate layer=9:1 to 3:7.

In the metallic material for electronic components of the presentinvention in yet another embodiment, in the range from the upper layerto the intermediate layer, exclusive of the range of 0.03 μm from theoutermost surface of the upper layer, C, S and O are each included in acontent of 2 at % or less.

In the metallic material for electronic components of the presentinvention in yet another embodiment, the indentation hardness of thesurface of the upper layer, namely, the hardness obtained by hitting adent on the surface of the upper layer with a load of 10 mN on the basisof a nanoindentation hardness test is 1000 MPa or more.

In the metallic material for electronic components of the presentinvention in yet another embodiment, the indentation hardness measuredfrom the surface of the upper layer, namely, the hardness obtained byhitting a dent on the surface of the upper layer with a load of 10 mN onthe basis of a nanoindentation hardness test is 10000 MPa or less.

In the metallic material for electronic components of the presentinvention, in yet another embodiment thereof, the arithmetic mean height(Ra) of the surface of the upper layer is 0.3 μm or less.

In the metallic material for electronic components of the presentinvention, in yet another embodiment thereof, the maximum height (Rz) ofthe surface of the upper layer is 3 μm or less.

In the metallic material for electronic components of the presentinvention in yet another embodiment, the upper layer, the intermediatelayer and the lower layer are formed, by forming a film of one or two ormore selected from the constituent element group A on the base material,then forming a film of one or two selected from the constituent elementgroup C, then forming a film of one or two or more selected from theconstituent element group B, and by diffusion of the respective selectedelements of the constituent element group A, the constituent elementgroup B and the constituent element group C.

In the metallic material for electronic components of the presentinvention in yet another embodiment, the diffusion is performed by heattreatment.

In the metallic material for electronic components of the presentinvention in yet another embodiment, the heat treatment is performed ata temperature equal to higher than the melting point(s) of the metal(s)of the constituent element group B, an alloy layer of one or twoselected from the constituent element group B and one or two or moreselected from the constituent element group A and an alloy layer of oneor two selected from the constituent element group B and one or two ormore selected from constituent element group C are formed.

In the metallic material for electronic components of the presentinvention in yet another embodiment, the content of the metal(s) of theconstituent element group A is 50% by mass or more in terms of the totalcontent of Ni, Cr, Mn, Fe, Co and Cu, and one or two or more selectedfrom the group consisting of B, P, Sn and Zn are further included.

In the metallic material for electronic components of the presentinvention in yet another embodiment, the content of the metal(s) of theconstituent element group B is 50% by mass or more in terms of the totalcontent of Sn and In, and the rest alloy component is composed of one ortwo or more selected from the group consisting of Ag, As, Au, Bi, Cd,Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Sb, W and Zn.

In the metallic material for electronic components of the presentinvention in yet another embodiment, the content of the metal(s) of theconstituent element group C is 50% by mass or more in terms of the totalcontent of Ag, Au, Pt, Pd, Ru, Rh, Os and Ir, and the rest alloycomponent is composed of one or two or more selected from the groupconsisting of Bi, Cd, Co, Cu, Fe, In, Mn, Mo, Ni, Pb, Sb, Se, Sn, W, Tland Zn.

In the metallic material for electronic components of the presentinvention, in yet another embodiment thereof, the Vickers hardness ofthe cross section of the lower layer is Hv 300 or more.

In the metallic material for electronic components of the presentinvention in yet another embodiment, the indentation hardness of thecross section of the lower layer, namely, the hardness obtained byhitting a dent on the cross section of the lower layer with a load of 10mN on the basis of a nanoindentation hardness test is 1500 MPa or more.

In the metallic material for electronic components of the presentinvention, in yet another embodiment thereof, the Vickers hardness ofthe cross section of the lower layer is Hv 1000 or less.

In the metallic material for electronic components of the presentinvention in yet another embodiment, the indentation hardness of thecross section of the lower layer, namely, the hardness obtained byhitting a dent on the cross section of the lower layer with a load of 10mN on the basis of a nanoindentation hardness test is 10000 MPa or less.

In the metallic material for electronic components of the presentinvention in yet another embodiment, the intermediate layer isconstituted with Ni₃Sn and Ni₃Sn₂.

In the metallic material for electronic components of the presentinvention in yet another embodiment, the intermediate layer isconstituted with Ni₃Sn₂.

In the metallic material for electronic components of the presentinvention in yet another embodiment, the intermediate layer isconstituted with Ni₃Sn₄.

In the metallic material for electronic components of the presentinvention in yet another embodiment, there is disposed, between thelower layer and the intermediate layer, a layer constituted with thealloy of the metal(s) of the constituent element group A and themetal(s) of the constituent element group C.

In the metallic material for electronic components of the presentinvention in yet another embodiment, P is deposited on the surface ofthe upper layer, and the deposition amount of P is 1×10⁻¹¹ to 4×10⁻⁸mol/cm².

In the metallic material for electronic components of the presentinvention in yet another embodiment, N is further deposited on thesurface of the upper layer, and the deposition amount of N is 2×10⁻¹² to8×10⁻⁹ mol/cm².

In the metallic material for electronic components of the presentinvention in yet another embodiment, in the XPS analysis performed forthe upper layer, with I(P2s) denoting the photoelectron detectionintensity due to the 2S orbital electron of P to be detected and I(N1s)denoting the photoelectron detection intensity due to the 1S orbitalelectron of N to be detected, the relation 0.1≤I(P2s)/I(N1s)≤1 issatisfied.

In the metallic material for electronic components of the presentinvention in yet another embodiment, in the XPS analysis performed forthe upper layer, with I(P2s) denoting the photoelectron detectionintensity due to the 2S orbital electron of P to be detected and I(N1s)denoting the photoelectron detection intensity due to the 1S orbitalelectron of N to be detected, the relation 1<I(P2s)/I(N1s)≤50 issatisfied.

Another aspect of the present invention is a method for producing themetallic material for electronic components, the metallic materialcomprising: a base material; a lower layer formed on the base material,the lower layer being constituted with one or two or more selected froma constituent element group A, namely, the group consisting of Ni, Cr,Mn, Fe, Co and Cu; an intermediate layer formed on the lower layer, theintermediate layer being constituted with one or two or more selectedfrom the constituent element group A and one or two selected from aconstituent element group B, namely, the group consisting of Sn and In;and an upper layer formed on the intermediate layer, the upper layerbeing constituted with one or two selected from the constituent elementgroup B and one or two or more selected from a constituent element groupC, namely, the group consisting of Ag, Au, Pt, Pd, Ru, Rh, Os and Ir,wherein the surface of the metallic material is surface-treated with aphosphoric acid ester-based solution including at least one of thephosphoric acid esters represented by the following general formulas [1]and [2], and at least one selected from the group of the cyclic organiccompounds represented by the following general formulas [3] and [4]:

(wherein, in formulas [1] and [2], R₁ and R₂ each represent asubstituted alkyl group and M represents a hydrogen atom or an alkalimetal atom,)

(wherein, in formulas [3] and [4], R₁ represents a hydrogen atom, analkyl group or a substituted alkyl group; R₂ represents an alkali metalatom, a hydrogen atom, an alkyl group or a substituted alkyl group; R₃represents an alkali metal atom or a hydrogen atom; R₄ represents —SH,an alkyl group-substituted or aryl group-substituted amino group, orrepresents an alkyl-substituted imidazolylalkyl group; and R₅ and R₆each represent —NH₂, —SH or —SM (M represents an alkali metal atom).)

In the method for producing metallic material for electronic componentsof the present invention in an embodiment, the surface treatment withthe phosphoric acid ester-based solution is performed by applying thephosphoric acid ester-based solution to the upper layer.

In the method for producing metallic material for electronic componentsof the present invention in another embodiment, the surface treatmentwith the phosphoric acid ester-based solution is performed by conductingan electrolysis by immersing the metallic material after the formationof the upper layer in the phosphoric acid ester-based solution and usingas the anode the metallic material after the formation of the upperlayer.

The present invention is, in yet another aspect thereof, a connectorterminal using, in the contact portion thereof, the metallic materialfor electronic components of the present invention.

The present invention is, in yet another aspect thereof, a connectorusing the connector terminal of the present invention.

The present invention is, in yet another aspect thereof, an FFC terminalusing, in the contact portion thereof, the metallic material forelectronic components of the present invention.

The present invention is, in yet another aspect thereof, an FPC terminalusing, in the contact portion thereof, the metallic material forelectronic components of the present invention.

The present invention is, in yet another aspect thereof, an FFC usingthe FFC terminal of the present invention.

The present invention is, in yet another aspect thereof, an FPC usingthe FPC terminal of the present invention.

The present invention is, in yet another aspect thereof, an electroniccomponent using, in the electrode thereof for external connection, themetallic material for electronic components of the present invention.

The present invention is, in yet another aspect thereof, an electroniccomponent using the metallic material for electronic components of thepresent invention, in a push-in type terminal thereof for fixing a boardconnection portion to a board by pushing the board connection portioninto the through hole formed in the board, wherein a female terminalconnection portion and the board connection portion are providedrespectively on one side and the other side of a mounting portion to beattached to a housing.

Advantageous Effects of Invention

According to the present invention, it is possible to provide metallicmaterials for electronic components, having low degree of whiskerformation, low adhesive wear property and high durability, and connectorterminals, connectors and electronic components using such metallicmaterials.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic diagram illustrating the structure of a metallicmaterial for electronic components according to an embodiment of thepresent invention.

FIG. 2 is an XPS analysis chart of a metallic material for electroniccomponents according to the present invention.

FIG. 3 is a graph showing the relation between the deposition amountsand the detection intensities of the components of the post treatmentsolution of a metallic material for electronic components according tothe present invention.

FIG. 4 is a schematic diagram of the HAADF(High-Angle-Annular-Dark-Filed)-STEM (scanning transmission electronmicroscope) image of a metallic material for electronic componentsaccording to the present invention.

FIG. 5 is a schematic diagram of the STEM (scanning transmissionelectron microscope) line analysis results of a metallic material forelectronic components according to the present invention.

FIG. 6 is the phase diagram of Sn—Ag.

FIG. 7 is the phase diagram of Sn-Ni.

DESCRIPTION OF EMBODIMENTS

Hereinafter, the metallic materials for electronic components accordingto the embodiments of the present invention are described. As shown inFIG. 1, the metallic material 10 for electronic components according toan embodiment includes a base material 11, an lower layer 12 formed onthe base material 11, an intermediate layer 13 formed on the lower layer12 and an upper layer 14 formed on the intermediate layer 13.

<Structure of Metallic Material for Electronic Components>

(Base Material)

Usable examples of the base material 11 include, without beingparticularly limited to: metal base materials such as copper and copperalloys, Fe-based materials, stainless steel, titanium and titaniumalloys and aluminum and aluminum alloys. The base material 11 may beformed by combining a metal base material with a resin layer. Examplesof the base material formed by combining a metal base material with aresin layer include the electrode portions in FPC and FFC basematerials.

(Upper Layer)

The upper layer 14 is required to be constituted with an alloy composedof one or two selected from a constituent element group B, namely, thegroup consisting of Sn and In, and one or two or more selected from aconstituent element group C, namely, the group consisting of Ag, Au, Pt,Pd, Ru, Rh, Os and Ir.

Sn and In are oxidizable metals, but are characterized by beingrelatively soft among metals. Accordingly, even when an oxide film isformed on the surface of Sn or In, for example at the time of joiningtogether a male terminal and a female terminal by using a metallicmaterial for electronic components as a contact material, the oxide filmis easily scraped to result in contact between metals, and hence a lowcontact resistance is obtained.

Sn and In are excellent in the gas corrosion resistance against thegases such as chlorine gas, sulfurous acid gas and hydrogen sulfide gas;for example, when Ag poor in gas corrosion resistance is used for theupper layer 14, Ni poor in gas corrosion resistance is used for thelower layer 12, and copper or a copper alloy poor in gas corrosionresistance is used for the base material 11, Sn and In have an effect toimprove the gas corrosion resistance of the metallic material forelectronic components. As for Sn and In, Sn is preferable because In isseverely regulated on the basis of the technical guidelines for theprevention of health impairment prescribed by the Ordinance of Ministryof Health, Labour and Welfare.

Ag, Au, Pt, Pd, Ru, Rh, Os and Ir are characterized by being relativelyheat-resistant among metals. Accordingly, these metals suppress thediffusion of the composition of the base material 11, the lower layer 12and the intermediate layer 13 toward the side of the upper layer 14 toimprove the heat resistance. These metals also form compounds with Sn orIn in the upper layer 14 to suppress the formation of the oxide film ofSn or In, so as to improve the solder wettability. Among Ag, Au, Pt, Pd,Ru, Rh, Os and Ir, Ag is more desirable from the viewpoint of electricalconductivity. Ag is high in electrical conductivity. For example, whenAg is used for high-frequency wave signals, impedance resistance is madelow due to the skin effect.

The thickness of the upper layer 14 is required to be 0.02 μm or moreand less than 1.00 μm. When the thickness of the upper layer 14 is lessthan 0.02 μm, the composition of the base material 11 or the lower layer12 tends to diffuse to the side of the upper layer 14 and the heatresistance or the solder wettability is degraded. Additionally, theupper layer is worn by fine sliding, and the lower layer 12 high incontact resistance tends to be exposed, and hence the fine sliding wearresistance is poor and the contact resistance tends to be increased byfine sliding. Moreover, the lower layer 12 poor in gas corrosionresistance tends to be exposed, and hence the gas corrosion resistanceis poor, and the exterior appearance is discolored when a gas corrosiontest is performed. On the other hand, when the thickness of the upperlayer 14 is 1.00 μm or more, the thin film lubrication effect due to thehard base material 11 or the hard lower layer 12 is degraded and theadhesive wear is increased. The mechanical durability is also degradedand scraping of plating tends to occur.

The upper layer 14 preferably includes the metal(s) of the constituentelement group B in a content of 10 to 50 at %. When the content of themetal(s) of the constituent element group B is less than 10 at %, forexample, in the case where the metal of the constituent element group Cis Ag, the gas corrosion resistance is poor, and sometimes the exteriorappearance is discolored when a gas corrosion test is performed. On theother hand, when the content of the metal(s) of the constituent elementgroup B exceeds 50 at %, the proportion of the metal(s) of theconstituent element group B in the upper layer 14 is large, and hencethe adhesive wear is increased and whiskers also tend to occur.Moreover, the fine sliding wear resistance is sometimes poor.

In the upper layer 14, the ζ(zeta)-phase being a Sn—Ag alloy includingSn in a content of 11.8 to 22.9 at % is preferably present. By thepresence of the ζ(zeta)-phase, the gas corrosion resistance is improved,and the exterior appearance is hardly discolored even when the gascorrosion test is performed.

In the upper layer 14, the ζ(zeta)-phase and the ε(epsilon)-phase beingAg₃Sn are preferably present. By the presence of the ε(epsilon)-phase,as compared with the case where only the ζ(zeta)-phase is present in theupper layer 14, the coating becomes harder and the adhesive wear isdecreased. The increase of the proportion of Sn in the upper layer 14improves the gas corrosion resistance.

In the upper layer 14, preferably only the ε(epsilon)-phase being Ag₃Snis present. By the sole presence of the ε(epsilon)-phase in the upperlayer 14, the coating becomes further harder and the adhesive wear isdecreased as compared with the case where the ζ(zeta)-phase and theε(epsilon)-phase being Ag₃Sn are present in the upper layer 14. The moreincrease of the proportion of Sn in the upper layer 14 also improves thegas corrosion resistance.

The presence of the ε(epsilon)-phase being Ag₃Sn and the β-Sn being a Snsingle phase in the upper layer 14 is preferable. By the presence of theε(epsilon)-phase being Ag₃Sn and β-Sn being a Sn single phase, the gascorrosion resistance is improved with a furthermore increase of theproportion of Sn in the upper layer as compared with the case where onlythe ε(epsilon)-phase is present in the upper layer 14.

In the upper layer 14, preferably the ζ(zeta)-phase being a Sn—Ag alloyincluding Sn in a content of 11.8 to 22.9 at %, the ε(epsilon)-phasebeing Ag₃Sn and β-Sn being a Sn single phase are present. By thepresence of the ζ(zeta)-phase, the ε(epsilon)-phase being Ag₃Sn and β-Snbeing a Sn single phase, the gas corrosion resistance is improved, theexterior appearance is hardly discolored even when a gas corrosion testis performed, and the adhesive wear is decreased. The compositionconcerned is created by diffusion and involves no structure in anequilibrium state.

The upper layer 14 should not be present as solely composed of β-Sn.When the upper layer 14 is present as solely composed of β-Sn, theadhesive wear is significant, whiskers occur and, for example, the heatresistance and the fine sliding wear resistance are degraded.

(Intermediate Layer)

Between the lower layer 12 and the upper layer 14, the intermediatelayer 13 constituted with one or two or more selected from theconstituent element group A, namely, the group consisting of Ni, Cr, Mn,Fe, Co and Cu, and one or two selected from the constituent elementgroup B, namely, the group consisting of Sn and In is required to beformed in a thickness of 0.01 μm or more and less than 0.40 μm. Sn andIn are excellent in the gas corrosion resistance against chlorine gasessuch as sulfurous acid gas and hydrogen sulfide gas; for example, whenNi poor in gas corrosion resistance is used for the lower layer 12 andcopper and copper alloy poor in gas corrosion resistance is used for thebase material 11, Sn and In have a function to improve the gas corrosionresistance of the metallic material for electronic components. Ni, Cr,Mn, Fe, Co and Cu provide a harder coating as compared with Sn and In,accordingly make the adhesive wear hardly occur, prevent the diffusionof the constituent metal(s) of the base material 11 into the upper layer14, and thus improve the durability in such a way that the degradationof the heat resistance or the degradation of the solder wettability issuppressed.

When the thickness of the intermediate layer 13 is 0.01 μm or more, thecoating becomes hard and the adhesive wear is decreased. On the otherhand, the thickness of the intermediate layer 13 is 0.40 μm or more, thebending processability is degraded, the mechanical durability is alsodegraded, and sometimes scraping of plating occurs.

Of Sn and In, Sn is preferable because In is severely regulated on thebasis of the technical guidelines for the prevention of healthimpairment prescribed by the Ordinance of Ministry of Health, Labour andWelfare. Ni is preferable among Ni, Cr, Mn, Fe, Co and Cu. This isbecause Ni is hard, and accordingly the adhesive wear hardly occurs andsufficient bending processability is obtained.

In the intermediate layer 13, the content of the metal(s) of theconstituent element group B is preferably 35 at % or more. When thecontent of Sn is 35 at % or more, sometimes the coating becomes hard andthe adhesive wear is decreased.

The intermediate layer 13 may be constituted with Ni₃Sn and Ni₃Sn₂, ormay also be constituted with Ni₃Sn₂ or Ni₃Sn₄ alone. The presence ofNi₃Sn, Ni₃Sn₂ or Ni₃Sn₄ sometimes improves the heat resistance or thesolder wettability.

In the intermediate layer 13, Ni₃Sn₄ and β-Sn being a Sn single phaseare preferably present. The presence of Ni₃Sn₄ and β-Sn sometimesimproves the heat resistance or the solder wettability as compared withthe case where Ni₃Sn₄ and Ni₃Sn₂ are present.

(Relation Between Thickness of Upper Layer and Minimum Thickness ofUpper Layer)

The minimum thickness (μm) of the upper layer 14 preferably accounts for50% or more of the thickness (μm) of the upper layer 14. When theminimum thickness of the upper layer 14 is less than 50% of thethickness of the upper layer 14, the surface roughness of the upperlayer 14 is rough, Ni high in contact resistance, hardly wettable withsolder and poor in gas corrosion resistance is exposed to the surface,and hence sometimes the heat resistance, the solder wettability and thegas corrosion resistance are degraded.

Here, the spot for grasping the relation between the thickness of theupper layer 14 and the minimum thickness of the upper layer 14 is theaverage cross section of the portion exhibiting the effect of thecoating of the present invention. The spot refers to the portionnormally subjected to film formation processing in the normal surfaceprofile (oil pits, etch pits, scratches, dents, and other surfacedefects are not included) of the material, in the portion concerned.Needless to say, the spot excludes the deformed potions or the like dueto the press processing before and after the film formation.

(Relation Between Thickness of Upper Layer and Maximum Value ofElevation Differences Between Adjacent Hills and Valleys in Profile ofInterface between Upper Layer and Intermediate Layer)

The maximum value (μm) of the elevation differences between the adjacenthills and valleys in the profile of the interface between the upperlayer 14 and the intermediate layer 13 preferably accounts for 50% orless of the thickness (μm) of the upper layer 14. When the maximum value(μm) of the elevation differences between the adjacent hills and valleysin the profile of the interface between the upper layer 14 and theintermediate layer 13 exceeds 50% of the thickness of the upper layer14, the intermediate layer 13 is to be positioned near the upper layer14, Ni high in contact resistance, hardly wettable with solder and poorin gas corrosion resistance tends to be exposed to the surface, andhence sometimes the heat resistance, solder wettability and gascorrosion are degraded.

The microscopic distribution of the thickness of the upper layer 14 andthe profile of the interface between the upper layer 14 and theintermediate layer 13 can be controlled by the film formation conditionsof the lower layer 12, intermediate layer 13 and upper layer 14. At thetime of film formation, by regulating the plating conditions (metalconcentration, additives, cathode current density, stirring and thelike), smooth electrodeposition film formation is performed so as tosatisfy the above-described “relation between the thickness of the upperlayer and the minimum thickness of the upper layer,” and theabove-described “relation between the thickness of the upper layer andthe maximum value of the elevation differences between the adjacenthills and valleys in the profile of the interface between the upperlayer and the intermediate layer.”

(Thickness Ratio Between Upper Layer and Intermediate Layer, andComposition)

The thickness ratio between the upper layer 14 and the intermediatelayer 13 is preferably such that upper layer/intermediate layer=9:1 to3:7. When the proportion of the upper layer exceeds 9/10, the thin filmlubrication effect due to the intermediate layer 13 harder than the hardbase material 11, lower layer 12 and upper layer 14 is degraded and theadhesive wear is increased. On the other hand, when the proportion ofthe upper layer is less than 3/10, Ni high in contact resistance, hardlywettable with solder and poor in gas corrosion resistance tends to beexposed to the surface, and hence sometimes the heat resistance, solderwettability, fine sliding wear resistance and gas corrosion aredegraded.

In the range from the upper layer 14 to the intermediate layer 13,exclusive of the range of 0.03 μm from the outermost surface of theupper layer 14, C, S and O are each included preferably in a content of2 at % or less. When the content of each of C, S and O is larger than 2at %, these co-deposited elements are gasified in the application ofheat treatment, and no uniform alloy coating may be able to be formed.

(Lower Layer)

Between the base material 11 and the upper layer 14, it is necessary toform the lower layer 12 constituted with one or two or more selectedfrom the constituent element group A, namely, the group consisting ofNi, Cr, Mn, Fe, Co and Cu. By forming the lower layer 12 with one or twoor more metals selected from the constituent element group A, namely,the group consisting of Ni, Cr, Mn, Fe, Co and Cu, the hard lower layer12 is formed, hence the thin film lubrication effect is improved and theadhesive wear is decreased, and the lower layer 12 prevents thediffusion of the constituent metal(s) of the base material 11 into theupper layer 14 and improves, for example, the heat resistance or thesolder wettability.

The thickness of the lower layer 12 is required to be 0.05 μm or more.When the thickness of the lower layer 12 is less than 0.05 μm the thinfilm lubrication effect due to the hard lower layer is degraded and theadhesive wear is increased. The diffusion of the constituent metal(s) ofthe base material 11 into the upper layer 14 is facilitated, and theheat resistance or the solder wettability is degraded. On the otherhand, the thickness of the lower layer 12 is required to be less than5.00 μm. When the thickness is 5.00 μm or more, bending processabilityis poor.

On the surface of the upper layer 14, a region where the total atomicconcentration (at %) of the constituent elements B≥the total atomicconcentration (at %) of the constituent elements C and the atomicconcentration (at %) of O≥10 at % is preferably present in the range of0.02 μm or less. The constituent elements B such as Sn has affinity withO, and hence the surface is bonded to O after Sn plating. Even when heattreatment is applied, the oxide of Sn formed by this bonding does notundergo Sn—Ag alloying and maintains the state before the heattreatment, the above-described region is present. However, when theregion concerned exceeds the range of 0.02 μm, sometimes the contactresistance or the solder wettability is degraded.

Between the lower layer 12 and the intermediate layer 13, a layerconstituted with the metal(s) of the constituent element group A and themetal(s) of the constituent element group C may also be provided. As thelayer concerned, for example, a Ni—Ag alloy layer is preferable. Whensuch a layer is formed between the lower layer 12 and the intermediatelayer 13, the diffusion of the constituent metal(s) of the base material11 into the upper layer 14 is further satisfactorily prevented, and forexample, the heat resistance or the solder wettability is improved.

(Constituent Element Group A)

The metal(s) of the constituent element group A includes Ni, Cr, Mn, Fe,Co and Cu in the total amount of these of 50 mass % or more, and mayfurther include one or two or more selected from the group consisting ofB, P, Sn and Zn. The alloy composition of the lower layer 12 having sucha constitution as described above makes the lower layer 12 harder andfurther improves the thin film lubrication effect to further decreasethe adhesive wear; the alloying of the lower layer 12 further preventsthe diffusion of the constituent metals of the base material 11 into theupper layer, and sometimes improves the durability such as the heatresistance and the solder wettability in such a way.

(Constituent Element Group B)

The content of the metal(s) of the constituent element group B is 50% bymass or more in terms of the total content of Sn and In, and the restalloy component may be composed of one or two or more selected from thegroup consisting of Ag, As, Au, Bi, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb,Sb, W and Zn. Sometimes, these metals further decreases the adhesivewear, suppresses the occurrence of whisker, and additionally improvesthe durability such as the heat resistance or the solder wettability.

(Constituent Element Group C)

The content of the metal(s) of the constituent element group C is 50% bymass or more in terms of the total content of Ag, Au, Pt, Pd, Ru, Rh, Osand Ir, and the rest alloy component may be composed of one or two ormore selected from the group consisting of Bi, Cd, Co, Cu, Fe, In, Mn,Mo, Ni, Pb, Sb, Se, Sn, W, Tl and Zn. Sometimes, these metals furtherdecreases the adhesive wear, suppresses the occurrence of whisker, andadditionally improves the durability such as the heat resistance or thesolder wettability.

(Diffusion Treatment)

The upper layer 14, the intermediate layer 13 and the lower layer 12 maybe formed, by forming a film of one or two or more selected from theconstituent element group A on the base material, then forming a film ofone or two selected from the constituent element group C, then forming afilm of one or two or more selected from the constituent element groupB, and by diffusion of the respective selected elements of theconstituent element group A, the constituent element group B and theconstituent element group C. For example, when the metal from theconstituent element group B is Sn and the metal from the constituentelement group C is Ag, the diffusion of Ag into Sn is fast, and thus aSn—Ag alloy layer is formed by spontaneous diffusion of Sn. Theformation of the alloy layer can further reduce the adhesion force ofSn, and the low degree of whisker formation and the durability can alsobe further improved.

(Heat Treatment)

After the formation of the upper layer 14, a heat treatment may beapplied for the purpose of further suppressing the adhesive wear andfurther improving the low degree of whisker formation and thedurability. The heat treatment allows the metal(s) of the constituentelement group B and the metal(s) of the constituent element group C ofthe upper layer 14 to form an alloy layer more easily, also allows themetal(s) of the constituent element group A and the metal(s) of theconstituent element group B of the intermediate layer 13 to form analloy layer more easily, further reduces the adhesion force of Sn, andcan further improve the low degree of whisker formation and thedurability.

For the heat treatment, the treatment conditions (temperature×time) canbe appropriately selected. The heat treatment is not particularlyrequired to be applied. When the heat treatment is applied, the heattreatment performed at a temperature equal to or higher than the highestmelting point of the metal(s) selected from the constituent elementgroup B allows the metal(s) of the constituent element group B and themetal(s) of the constituent element group C of the upper layer 14 toform an alloy layer more easily, and also allows the metal(s) of theconstituent element group A and the metal(s) of the constituent elementgroup B of the intermediate layer 13 to form an alloy layer more easily.

(Post-Treatment)

To the upper layer 14, or to the upper layer 14 after being subjected toheat treatment, a post-treatment may be applied for the purpose offurther decreasing the adhesive wear and improving the low degree ofwhisker formation and the durability. The post-treatment improves thelubricity, further decreases the adhesive wear, suppress the oxidationof the upper layer 14, and can improve the durability such as the heatresistance or the solder wettability. Specific examples of thepost-treatment include phosphoric acid salt treatment, lubricationtreatment and silane coupling treatment using an inhibitor. For thepost-treatment, the treatment conditions (temperature×time) can beappropriately selected. The post-treatment is not particularly requiredto be applied.

The post-treatment is preferably performed for the surface of the upperlayer 14 by using an aqueous solution (referred to as the phosphoricacid ester-based solution) including one or two or more phosphoric acidesters and one or two or more cyclic organic compounds. The phosphoricacid ester(s) added to the phosphoric acid ester-based solution playsthe functions as an antioxidant for plating and a lubricant for plating.The phosphoric acid esters used in the present invention are representedby the general formula [1] and [2]. Examples of the preferable compoundsamong the compounds represented by the general formula [1] includelauryl acidic phosphoric acid monoester. Examples of the preferablecompounds among the compounds represented by the general formula [2]include lauryl acidic phosphoric acid diester.

(wherein, in formulas [1] and [2], R₁ and R₂ each represent asubstituted alkyl group and M represents a hydrogen atom or an alkalimetal atom.)

The cyclic organic compound added to the phosphoric acid ester-basedsolution plays the function as an antioxidant for plating. The group ofthe cyclic organic compounds used in the present invention arerepresented by the general formula [3] and [4]. Examples of thepreferable compounds among the cyclic organic compounds represented bythe general formulas [3] and [4] include: mercaptobenzothiazole, Na saltof mercaptobenzothiazole, K salt of mercaptobenzothiazole,benzotriazole, 1-methyltriazole, tolyltriazole and triazine-basedcompounds.

(wherein, in formulas [3] and [4], R₁ represents a hydrogen atom, analkyl group or a substituted alkyl group; R₂ represents an alkali metalatom, a hydrogen atom, an alkyl group or a substituted alkyl group; R₃represents an alkali metal atom or a hydrogen atom; R₄ represents —SH,an alkyl group-substituted or aryl group-substituted amino group, orrepresents an alkyl-substituted imidazolylalkyl group; and R₅ and R₆each represent —NH₂, —SH or —SM (M represents an alkali metal atom).)

The post-treatment is furthermore preferably performed in such a waythat both P and N are present on the surface of the upper layer 14. WhenP is absent on the plating surface, the solderability tends to bedegraded, and the lubricity of the plating material is also degraded. Onthe other hand, when N is absent on the Sn or Sn alloy plating surface,sometimes the contact resistance of the plating material tends to beincreased in a high temperature environment.

Moreover, in the present invention, in the case where P is deposited onthe surface of the upper layer 14, when the deposition amount of P is1×10⁻¹¹ to 4×10⁻⁸ mol/cm², preferably the solderability is hardlydegraded, the lubricity is satisfactory and the increase of the contactresistance is also reduced. In the case where N is additionallydeposited on the surface of the upper layer 14, more preferably thedeposition amount of N is 2×10⁻¹² to 8×10⁻⁹ mol/cm². When the depositionamount of P is less than 1×10⁻¹¹ mol/cm², the solder wettability tendsto be degraded, and when the deposition amount of P exceeds 4×10⁻⁸mol/cm², sometimes the failure of the increase of the contact resistanceoccurs.

When in the XPS analysis performed for the upper layer 14, with I(P2s)denoting the photoelectron detection intensity due to the 2S orbitalelectron of P to be detected and I(N1s) denoting the photoelectrondetection intensity due to the 1S orbital electron of N to be detected,the relation 0.1≤I(P2s)/I(N1s)≤1 is satisfied, sometimes the contactresistance and the solderability of the plating material is hardlydegraded in a high temperature environment. When the value ofI(P2s)/I(N1s) is less than 0.1, for example, the function to prevent thecontact resistance degradation is not sufficient, and when the value ofI(P2s)/I(N1s) exceeds 1, the contact resistance at the early stage comesto be slightly high, but, as described below, sometimes the dynamicfriction coefficient of the plating material comes to be small. In thiscase, I(P2s) and I(N1s) more preferably satisfy the relation0.3≤I(P2s)/I(N1s)≤0.8.

When in the XPS analysis performed, in the same manner as describedabove, for the upper layer 14, with I(P2s) denoting the photoelectrondetection intensity due to the 2S orbital electron of P to be detectedand I(N1s) denoting the photoelectron detection intensity due to the 1Sorbital electron of N to be detected, the relation 1≤I(P2s)/I(N1s)≤50 issatisfied, sometimes the dynamic friction coefficient of the platingmaterial comes to be small and the insertion force of terminals andconnectors comes to be low. When the value of I(P2s)/I(N1s) is 1 orless, the insertion force comes to be slightly high, and when the valueof I(P2s)/I(N1s) exceeds 50, the insertion force comes to be low, butsometimes the contact resistance at the early stage comes to be high andthe solderability at the early stage is also degraded. In this case,I(P2s) and I(N1s) more preferably satisfy the relation5<I(P2s)/I(N1s)≤40.

The concentration of the phosphoric acid ester(s) for obtaining thedeposition amounts of the post-treatment solution components on thesurface of the upper layer 14 of the present invention is 0.1 to 10 g/L,and preferably 0.5 to 5 g/L. On the other hand, the concentration of thecyclic organic compound(s) is, in relation to the total volume of thetreatment solution, 0.01 to 1.0 g/L and preferably 0.05 to 0.6 g/L.

The phosphoric acid ester-based solution is an aqueous solution havingthe above-described components, and when the solution is heated toincrease the temperature of the solution to 40 to 80° C., theemulsification of the components into water proceed faster, and thedrying of the materials after the treatment is facilitated.

The surface treatment may also be performed by applying the phosphoricacid ester-based solution to the surface of the upper layer 14 after theformation of the upper layer 14. Examples of the method for applying thesolution concerned include: spray coating, flow coating, dip coating androll coating; from the viewpoint of productivity, dip coating or spraycoating is preferable. On the other hand, as another treatment method,the surface treatment with the phosphoric acid ester-based solution mayalso be performed by conducting an electrolysis by immersing themetallic material after the formation of the upper layer 14 in thephosphoric acid ester-based solution and using as the anode the metallicmaterial after the formation of the upper layer 14. The metallicmaterial subjected to the treatment based on this method offers anadvantage that the contact resistance in a high temperature environmentis more hardly increased.

The hitherto presented description of the surface treatment with thephosphoric acid ester-based solution may be performed either after theformation of the upper layer 14 or after the reflow treatment subsequentto the formation of the upper layer 14. The surface treatment is notparticularly temporarily limited, but from industrial viewpoint, thesurface treatment is preferably performed as a sequence of steps.

<Properties of Metallic Material for Electronic Components>

The indentation hardness of the surface of the upper layer 14, namely,the hardness obtained by hitting a dent on the surface of the upperlayer 14 with a load of 10 mN on the basis of a nanoindentation hardnesstest is preferably 1000 MPa or more. The indentation hardness being 1000MPa or more improves the thin film lubrication effect due to the hardupper layer 14, and decreases the adhesive wear. The indentationhardness of the surface of the upper layer 14 is preferably 10000 MPa orless. The indentation hardness of the surface of the upper layer 14being 10000 MPa improves the bending processability, makes cracks hardlyoccur in the molded portion when the metallic material for electroniccomponents of the present invention is subjected to press molding, andconsequently suppresses the degradation of the gas corrosion resistance.

The arithmetic mean height (Ra) of the surface of the upper layer 14 ispreferably 0.3 μm or less. The arithmetic mean height (Ra) of thesurface of the upper layer 14 being 0.3 μm or less reduces the raisedportions of the surface relatively tending to be corroded, thus smoothesthe surface and improves the gas corrosion resistance.

The maximum height (Rz) of the surface of the upper layer 14 ispreferably 3 μm or less. The maximum height (Rz) of the surface of theupper layer 14 being 3 μm or less reduces the raised portions relativelytending to be corroded, thus smoothes the surface and improves the gascorrosion resistance.

The Vickers hardness of the lower layer 12 is preferably Hv 300 or more.The Vickers hardness of the lower, layer 12 being Hv 300 or more makesthe lower layer harder and further improves the thin film lubricationeffect to further decrease the adhesive wear. On the other hand, theVickers hardness Hv1000 of the lower layer 12 is preferably Hv 1000 orless. The Vickers hardness of the lower layer 12 being Hv 1000 or lessimproves the bending processability, makes cracks hardly occur in themolded portion when the metallic material for electronic components ofthe present invention is subjected to press molding, and consequentlysuppresses the degradation of the gas corrosion resistance.

The indentation hardness of the cross section of the lower layer 12 ispreferably 1500 MPa or more. The indentation hardness of the crosssection of the lower layer 12 being 1500 MPa or more makes the lowerlayer harder and further improves the thin film lubrication effect anddecreases the adhesive wear. On the other hand, the indentation hardnessof the cross section of the lower layer 12 is preferably 10000 MPa orless. The indentation hardness of the cross section of the lower layer12 being 10000 MPa or less improves the bending processability, makescracks hardly occur in the molded portion when the metallic material forelectronic components of the present invention is subjected to pressmolding, and consequently suppresses the degradation of the gascorrosion resistance.

<Applications of Metallic Material for Electronic Components>

Examples of the application of the metallic material for electroniccomponents of the present invention include, without being particularlylimited to: a connector terminal using, in the contact portion thereof,the metallic material for electronic components, an FFC terminal or anFPC terminal using, in the contact portion thereof, the metallicmaterial for electronic components, and an electronic component using,in the electrode thereof for external connection, the metallic materialfor electronic components. The terminal does not depend on theconnection mode on the wiring side as exemplified by a crimp-typeterminal, a soldering terminal and a press-fit terminal. Examples of theelectrode for external connection include a connection componentprepared by applying a surface treatment to a tab, and material surfacetreated for use in under bump metal of a semiconductor.

Connectors may also be prepared by using such connector terminals formedas described above, and an FFC or an FPC may also be prepared by usingan FFC terminal or an FPC terminal.

The metallic material for electronic components of the present inventionmay also be used in a push-in type terminal for fixing a boardconnection portion to a board by pushing the board connection portioninto the through hole formed in the board, wherein a female terminalconnection portion and the board connection portion are providedrespectively on one side and the other side of a mounting portion to beattached to a housing.

In a connector, both of the male terminal and the female terminal may bemade of the metallic material for electronic components of the presentinvention, or only one of the male terminal and the female terminal maybe made of the metallic material for electronic components of thepresent invention. The use of the metallic material for electroniccomponents of the present invention for both of the male terminal andthe female terminal further improves the low degree ofinsertion/extraction force.

<Method for Producing Metallic Material for Electronic Components>

As the method for producing the metallic material for electroniccomponents of the present invention, for example, either a wet plating(electroplating or electroless plating) or a dry plating (sputtering orion plating) can be used.

EXAMPLES

Hereinafter, both Examples of the present invention and ComparativeExamples are presented; these Examples and Comparative Examples areprovided for better understanding of the present invention, and are notintended to limit the present invention.

As Examples, Reference Examples and Comparative Examples, under theconditions shown in Table 1, the surface treatment was performed in thesequence of electrolytic degreasing, acid cleaning, first plating,second plating, third plating and heat treatment.

(Materials)

(1) Plate: thickness: 0.30 mm, width: 30 mm, component: Cu-30Zn

(2) Male terminal: thickness: 0.64 mm, width: 2.3 mm, component: Cu-30Zn

(3) Push-in type terminal: Press-fit terminal PCB connector, R800,manufactured by Tokiwa & Co., Inc.

(First Plating Conditions)

(1) Semi-Glossy Ni Plating

Surface treatment method: Electroplating

Plating solution: Ni sulfamate plating solution+saccharin

Plating temperature: 55° C.

Electric current density: 0.5 to 4 A/dm²

(2) Glossy Ni Plating

Surface treatment method: Electroplating

Plating solution: Ni sulfamate plating solution+saccharin+additives

Plating temperature: 55° C.

Electric current density: 0.5 to 4 A/dm²

(3) Cu Plating

Surface treatment method: Electroplating

Plating solution: Cu sulfate plating solution

Plating temperature: 30° C.

Electric current density: 0.5 to 4 A/dm²

(4) Matte Ni Plating

Surface treatment method: Electroplating

Plating solution: Ni sulfamate plating solution

Plating temperature: 55° C.

Electric current density: 0.5 to 4 A/dm²

(5) Ni-Plating

Surface treatment method: Electroplating

Plating solution: Ni sulfamate plating solution+phosphite

Plating temperature: 55° C.

Electric current density: 0.5 to 4 A/dm²

(Second Plating Conditions)

(1) Ag Plating

Surface treatment method: Electroplating

Plating solution: Ag cyanide plating solution

Plating temperature: 40° C.

Electric current density: 0.2 to 4 A/dm²

(2) Sn Plating

Surface treatment method: Electroplating

Plating solution: Sn methanesulfonate plating solution

Plating temperature: 40° C.

Electric current density: 0.5 to 4 A/dm²

(Third Plating Conditions)

(1) Sn Plating Conditions

Surface treatment method: Electroplating

Plating solution: Sn methanesulfonate plating solution

Plating temperature: 40° C.

Electric current density: 0.5 to 4 A/dm²

(Heat Treatment)

The heat treatment was performed by placing the sample on a hot plate,and verifying that the surface of the hot plate reached thepredetermined temperature.

(Post-Treatment)

For Examples 25 to 40, relative to Example 1, additionally a phosphoricacid ester-based solution was used as a surface treatment solution,application based on immersion or anode electrolysis (2 V,potentiostatic electrolysis) was performed, and thus the surfacetreatment of the plating surface was performed. The surface treatmentconditions in this case are shown in Table 2 presented below. Afterthese treatments, the samples were dried with warm air. For thedetermination of the amounts of P and N deposited on the platingsurface, first by using several samples having known deposition amounts,a quantitative analysis based on XPS (X-ray photoelectron analysismethod) was performed, and the detection intensities (number of countsdetected in 1 second) of P(2 s orbital) and N(1 s orbital) weremeasured. Next, on the basis of the thus obtained results, the relationsbetween the deposition amounts and the detection intensities werederived, and from these relations, the deposition amounts of P and N ofunknown samples were determined. FIG. 2 shows an example of the XPSanalysis results, and FIG. 3 shows the relations between the depositionamounts of the post-treatment solution components and the XPS detectionintensities (the unit of the deposition amount of P=1.1×10⁻⁹ mol/cm²;the unit of the deposition amount of N=7.8×10⁻¹¹ mol/cm²).

(Determination of Structures [Compositions] and Measurement ofThicknesses of Upper Layer and Intermediate Layer)

The determination of the structures and the measurement of thethicknesses of the upper layer and the intermediate layer of each of theobtained samples were performed by the line analysis based on the STEM(scanning transmission electron microscope) analysis. The analyzedelements are the elements in the compositions of the upper layer and theintermediate layer, and C, S and O. These elements are defined as thespecified elements. On the basis of the total concentration of thespecified elements defined as 100%, the concentrations (at %) of therespective elements were analyzed. The thickness corresponds to thedistance determined from the line analysis (or area analysis). As theSTEM apparatus, the JEM-2100F manufactured by JEOL Ltd. was used. Theacceleration voltage of this apparatus is 200 kV.

In the determination of the structures and measurement of thethicknesses of the upper layer and the intermediate layer of each of theobtained samples, the evaluations were performed for arbitrary 10 pointsand the resulting values were averaged.

(Measurement of Thickness of Lower Layer)

The thickness of the lower layer was measured with the X-ray fluorescentanalysis thickness meter (SEA5100, collimator: 0.1 mmΦ, manufactured bySeiko Instruments Inc.).

In the measurement of the thickness of the lower layer, the evaluationswere performed for arbitrary 10 points and the resulting values wereaveraged.

(Evaluations)

For each of the samples, the following evaluations were performed.

A. Adhesive Wear

The adhesive wear was evaluated by performing an insertion/extractiontest for each of the plated male terminals according to Examples andComparative Examples by using a commercially available Sn reflow platingfemale terminal (090 type Sumitomo TS/Yazaki 090II Series femaleterminal, non-waterproofing/F090-SMTS).

The measurement apparatus used in the test was the 1311NR manufacturedby Aikoh Engineering Co., Ltd., and the evaluation was performed with asliding distance of a male pin of 5 mm. The number of the samples wasset at five, and the adhesive wear was evaluated by using the insertionforce. As the insertion force, the averaged value of the maximum valuesof the respective samples was adopted. As the blank material of theadhesive wear, the sample of Comparative Example 11 was adopted.

The intended target of the adhesive wear is less than 85% of the maximuminsertion/extraction force of Comparative Example 11. This is becausethe insertion/extraction force of Comparative Example 3 was 90% of themaximum insertion force of Comparative Example 11, and a largerreduction of the insertion/extraction force than the reduction of theinsertion/extraction force in Comparative Example 3 was adopted as theintended target.

B. Whiskers

Whiskers were evaluated by the load test (ball indenter method) of JEITARC-5241. Specifically, each of the samples was subjected to the loadtest, and each of the samples subjected to the load test was observedwith a SEM (model JSM-5410, manufactured by JEOL Ltd.) at amagnification of 100× to 10000λ, and thus the occurrence state of thewhiskers was observed. The load test conditions are shown below.

Diameter of ball indenter: Φ 1 mm±0.1 mm

Test load: 2 N±0.2 N

Test time: 120 hours

Number of samples: 10

The intended property is such that no whiskers 20 μm or more in lengthoccurs, and the biggest intended target is such that no whiskers of anylength occurs.

C. Contact Resistance

The contact resistance was measured with the contact simulator modelCRS-113-Au manufactured by Yamasaki-seiki Co., Ltd., under the conditionof the contact load of 50 kg, on the basis of the four-terminal method.The number of the samples was set at five, and the range from theminimum value to the maximum value of each of the samples was adopted.The intended target was the contact resistance of 10 mΩ or less.

D. Heat Resistance

The heat resistance was evaluated by measuring the contact resistance ofa sample after an atmospheric heating (200° C.×1000 h). The intendedproperty was the contact resistance of 10 mΩ or less, and the biggesttarget was such that the contact resistance was free from variation(equal) between before and after the heat resistance test.

E. Fine Sliding Wear Resistance

The fine sliding wear resistance was evaluated in terms of the relationbetween the number of the sliding operations and the contact resistanceby using the fine sliding tester model CRS-G2050 manufactured byYamasaki-seiki Co., Ltd., under the conditions of a sliding distance of0.5 mm, a sliding speed of 1 mm/s, a contact load of 1 N, and a numberof the back and forth sliding operations of 500. The number of thesamples was set at five, and the range from the minimum value to themaximum value of each of the samples was adopted. The intended propertywas such that the contact resistance was 100 mΩ or less at the time ofthe number of sliding operations of 100.

F. Solder Wettability

The solder wettability was evaluated for the samples after plating. Asolder checker (SAT-5000, manufactured by Rhesca Corp.) was used, acommercially available 25% rosin-methanol flux was used as a flux, andthe solder wetting time was measured by a meniscograph method. A solderSn-3Ag-0.5Cu (250° C.) was used. The number of the samples was set atfive, and the range from the minimum value to the maximum value of eachof the samples was adopted. The intended property was such that the zerocross time was 5 seconds (s) or less.

G. Gas Corrosion Resistance

The gas corrosion resistance was evaluated in the following testenvironment. The evaluation of the gas corrosion resistance was based onthe exterior appearance of each of the samples after the completion ofan environmental test. The intended property was such that the exteriorappearance is hardly discolored or somewhat discolored to a degreepractically causing no problem.

Hydrogen sulfide gas corrosion test

Hydrogen sulfide concentration: 10 ppm

Temperature: 40° C.

Humidity: 80% RH

Exposure time: 96 h

Number of samples: 5

H. Mechanical Durability

The mechanical durability was performed as follows. A push-in typeterminal was pushed into a through hole (board thickness: 2 mm, throughhole: Φ1 mm) and then extracted from the through hole, the cross sectionof the push-in type terminal was observed with a SEM (model JSM-5410,manufactured by JEOL Ltd.) at a magnification of 100× to 10000× and theoccurrence state of powder was examined. The case where the diameter ofthe powder was less than 5 μm was marked with “circle”, the case wherethe diameter of the powder was 5 μm or more and less than 10 μm wasmarked with “triangle”, and the case where the diameter of the powderwas 10 μm or more was marked with “X-mark”.

I. Bending Processability

The bending processability was evaluated by using a W-shaped mold on thebasis of the 90° bending under the condition that the ratio between theplate thickness of each of the samples and the bending radius was 1. Theevaluation was performed as follows: the surface of thebending-processed portion of each of the samples was observed with anoptical microscope, and the case where no cracks were observed andpractically no problems were determined to be involved was marked with“circle”, and the case where crack(s) was found was marked with“X-mark”. The case where “circle” and “X-mark” were hardlydistinguishable from each other was marked with “triangle”.

J. Vickers Hardness

The Vickers hardness of the lower layer was measured by pressing anindenter from the cross section of the lower layer of each of thesamples with a load of 980.7 mN (Hv 0.1) and a load retention time of 15seconds.

K. Indentation Hardness

The indentation hardness of the upper layer was measured with ananoindentation hardness tester (ENT-2100, manufactured by Elionix Inc.)by pressing an indenter onto the surface of each of the samples with aload of 10 mN.

The indentation hardness of the lower layer was measured by pressing anindenter from the cross section of the lower layer of each of thesamples with a load of 10 mN (Hv 0.1) and a load retention time of 15seconds.

L. Surface Roughness

The measurement of the surface roughness (the arithmetic mean height(Ra) and the maximum height (Rz)) was performed according to JIS B 0601,by using a noncontact three-dimensional measurement apparatus (modelNH-3, manufactured by Mitaka Kohki Co., Ltd.). The cutoff was 0.25 mm,the measurement length was 1.50 mm, and the measurement was repeatedfive times for one sample.

M. Relation Between Thickness of Upper Layer and Minimum Thickness ofUpper Layer

The relation between the thickness of the upper layer and the minimumthickness of the upper layer was evaluated by using a HAADF (high-angleannular dark-field) image based on the STEM (scanning transmissionelectron microscope) analysis. FIG. 4 shows a schematic diagram of theHAADF (high-angle annular dark-field). The evaluation was performed asfollows.

(1) In the evaluation, HAADF (high-angle annular dark-field) images at amagnification of 50 k were used, and the reference length of 3 μm/fieldof view was adopted.

(2) In the reference length of 3 μm/field of view, the minimum thicknesssite of the upper layer was identified. When the minimum thickness sitewas hardly identified, the site concerned was identified with amagnification, if necessary, elevated to a higher level.

(3) In order to precisely determine the minimum thickness of the upperlayer, the identified site was observed with a higher magnification. Byusing HAADF (high-angle annular dark-field) images at a magnification of100 to 200K, the “minimum thickness of the upper layer” was preciselydetermined.

(4) The relation between the above-described “thickness (μm) of theupper layer” determined by the line analysis based on the STEM (scanningtransmission electron microscope) analysis and the “minimum thickness(μm) of the upper layer” was grasped by measuring five fields of viewper one sample.

FIG. 4 schematically depicts the surface roughness of each of the layersas exaggerated than actual observation so as for the above-described (1)to (4) to be easily understood.

N. Relation Between Thickness of Upper Layer and Maximum Value ofElevation Differences Between Adjacent Hills and Valleys in Profile ofInterface Between Upper Layer and Intermediate Layer

The relation between the thickness of the upper layer and the maximumvalue of the elevation differences between the adjacent hills andvalleys in the profile of the interface between the upper layer and theintermediate layer was evaluated by using the HAADF (high-angle annulardark-field) image based on the STEM (scanning transmission electronmicroscope) analysis. FIG. 4 shows a schematic diagram of the HAADF(high-angle annular dark-field) image. The evaluation was performed asfollows.

(1) In the evaluation, HAADF (high-angle annular dark-field) images at amagnification of 50 k were used, and the reference length of 3 μm/fieldof view was adopted.

(2) In the reference length of 3 μm/field of view, the maximum valuesite of the elevation differences between the adjacent hills and valleysin the profile of the interface between the upper layer and theintermediate layer was identified. When the maximum value site of theelevation differences between the adjacent hills and valleys in theprofile of the interface between the upper layer and the intermediatelayer was hardly identified, the site concerned was identified with amagnification, if necessary, elevated to a higher level.

(3) In order to precisely determine the maximum value site of theelevation differences between the adjacent hills and valleys in theprofile of the interface between the upper layer and the intermediatelayer, the identified site was observed with a higher magnification. Byusing HAADF (high-angle annular dark-field) images at a magnification of100 to 200K, the “maximum value of the elevation differences between theadjacent hills and valleys in the profile of the interface between theupper layer and the intermediate layer” was precisely determined.

(4) The relation between the above-described “thickness (μm) of theupper layer” determined by the line analysis based on the STEM (scanningtransmission electron microscope) analysis and the “maximum value of theelevation differences between the adjacent hills and valleys in theprofile of the interface between the upper layer and the intermediatelayer” was grasped by measuring five fields of view per one sample.

FIG. 4 schematically depicts the surface roughness of each of the layersas exaggerated than actual observation so as for the above-described (1)to (4) to be easily understood.

The test conditions and the test results are shown in the tablespresented below. In the tables presented below, the “composition”represents the ratio between the respective atomic concentrations (at%).

TABLE 1 First plating Second plating Third plating Plating PlatingPlating Heat treatment conditions Thickness conditions Thicknessconditions Thickness Temperature Time No. [μm] No. [μm] No. [μm] [° C.][sec] Atmosphere Examples 1 1 1 1 0.22 1 0.14 300 3 The air 2 1 1 1 0.041 0.1 300 3 The air 3 1 1 1 0.5 1 0.2 300 10 The air 4 1 1 1 0.22 1 0.09300 3 The air 5 1 1 1 0.22 1 0.3 300 3 The air 6 1 1 1 0.22 1 0.45 300 3The air 7 1 0.07 1 0.22 1 0.14 300 3 The air 8 1 0.5 1 0.22 1 0.14 300 3The air 9 1 3 1 0.22 1 0.14 300 3 The air 10 1 1 1 0.35 1 0.14 300 3 Theair 11 1 1 1 0.1 1 0.2 300 3 The air 12 1 1 1 0.2 1 0.17 300 3 The air13 1 1 1 0.22 1 0.14 260 3 The air 14 1 1 1 0.22 1 0.14 280 3 The air 151 1 1 0.07 1 0.2 400 3 The air 16 2 1 1 0.22 1 0.14 300 3 The air 17 4 11 0.22 1 0.14 300 3 The air 18 1 1 1 0.22 1 0.14 300 3 The air 19 1 1 10.22 1 0.14 300 3 The air 20 3 1 1 0.22 1 0.14 300 3 The air 21 1 1 10.04 1 0.185 300 3 The air 22 1 1 1 0.22 1 0.14 255 3 The air 23 1 1 10.22 1 0.14 285 3 The air 24 1 1 1 0.25 1 0.11 600 0.5 The air 41 1 1 10.23 1 0.11 285 3 The air Reference 1 1 1 1 0.1 1 0.3 280 3 The airExamples 2 1 1 1 0.22 1 0.14 250 3 The air 3 1 1 1 0.7 1 0.2 350 5 Theair 4 1 1 1 0.05 1 0.2 280 3 The air 5 5 1 1 0.22 1 0.14 300 3 The air 61 1 1 0.04 1 0.185 300 3 The air 7 1 1 1 0.04 1 0.185 300 3 The air 8 11 1 0.22 1 0.14 300 3 100% Oxygen 9 1 1 1 0.02 1 0.05 300 3 The airComparative 1 1 1 1 0.01 1 0.05 300 3 The air Examples 2 1 1 1 1 1 0.3500 5 The air 3 1 1 2 0.6 300 5 The air 4 1 1 1 0.22 1 0.07 300 3 Theair 5 1 1 1 0.22 1 0.6 300 3 The air 6 1 0.03 1 0.22 1 0.14 300 3 Theair 7 1 5.5 1 0.22 1 0.14 300 3 The air 8 1 0.5 1 1 1 0.05 600 30 Theair 9 1 0.5 1 0.5 1 0.06 500 18 The air 11 4 1 2 1 300 5 The air

TABLE 2 Conditions of treatment with phosphoric acid ester- basedsolution Cyclic Intensity ratio Phosphoric organic Deposition DepositionI(P2s)/I(N1s) acid ester compound amount of P amount of N between P andN No. species species mol/cm² mol/cm² detected by XPS Examples 25 A1 B11 × 10⁻⁹ 8 × 10⁻¹¹ 1.13 26 A1 B1 3 × 10⁻⁹ 9 × 10⁻¹¹ 1.82 27 A2 B1 2 ×10⁻⁹ 8 × 10⁻¹¹ 1.40 28 A1 B2 2 × 10⁻⁹ 9 × 10⁻¹¹ 1.83 29 A1 B3 2 × 10⁻⁹ 8× 10⁻¹¹ 1.29 30 A1 B3  1 × 10⁻¹² 8 × 10⁻¹¹ 0.06 31 A1 B1  1 × 10⁻¹¹ 8 ×10⁻¹¹ 0.13 32 A1 B1 4 × 10⁻⁸ 8 × 10⁻¹¹ 10.67 33 A1 B1  7 × 10⁻¹⁰ 2 ×10⁻¹² 1.62 34 A1 B1 2 × 10⁻⁹ 8 × 10⁻¹¹ 1.47 35 A1 B1 2 × 10⁻⁹ 8 × 10⁻¹¹1.47 36 A1 B1  5 × 10⁻¹² 8 × 10⁻¹³ 1.00 37 A1 B1 8 × 10⁻⁸ 4 × 10⁻⁸  3.4938 A1 B1 9 × 10⁻⁷ 8 × 10⁻¹¹ 53.40 39 A1 — 2 × 10⁻⁹ — ∞ 40 — B1 — 8 ×10⁻¹¹ 0 *) In relation to “Conditions of treatment with phosphoric acidester-based solution,” in Example 34, anode electrolysis was performedat 2 V for 5 seconds, and in Examples other than Example 34, immersiontreatment was performed. A1: Lauryl acidic phosphoric acid monoester(phosphoric acid monolauryl ester) A2: Lauryl acidic phosphoric aciddiester (phosphoric acid dilauryl ester) B1: Benzotriazole B2: Na saltof mercaptobenzothiazole B3: Tolyltriazole

TABLE 3 Composition Thickness and thickness ratio between of layer upperlayer between Upper layer Intermediate layer and intermediate ThicknessThickness intermediate layer and lower Composition Structure [μm]Composition Structure [μm] layer layer Examples 1 Ag:Sn = 8:2 ζ-Phase +ε-phase 0.30 Sn:Ni = 7:3 N₃Sn₄ + β-Sn 0.07 8:2 — 2 Ag:Sn = 8:2 ζ-Phase +ε-phase 0.07 Sn:Ni = 7:3 N₃Sn₄ + β-Sn 0.07 5:5 — 3 Ag:Sn = 8:2 ζ-Phase +ε-phase 0.60 Sn:Ni = 7:3 N₃Sn₄ + β-Sn 0.07 9:1 — 4 Ag:Sn = 8:2 ζ-Phase +ε-phase 0.30 Sn:Ni = 7:3 N₃Sn₄ + β-Sn 0.04 88:12 — 5 Ag:Sn = 8:2ζ-Phase + ε-phase 0.30 Sn:Ni = 7:3 N₃Sn₄ + β-Sn 0.20 6:4 — 6 Ag:Sn = 8:2ζ-Phase + ε-phase 0.30 Sn:Ni = 7:3 N₃Sn₄ + β-Sn 0.35 46:54 — 7 Ag:Sn =8:2 ζ-Phase + ε-phase 0.30 Sn:Ni = 7:3 N₃Sn₄ + β-Sn 0.07 8:2 — 8 Ag:Sn =8:2 ζ-Phase + ε-phase 0.30 Sn:Ni = 7:3 N₃Sn₄ + β-Sn 0.07 8:2 — 9 Ag:Sn =8:2 ζ-Phase + ε-phase 0.30 Sn:Ni = 7:3 N₃Sn₄ + β-Sn 0.07 8:2 — 10 Ag:Sn= 85:15 ζ-Phase 0.30 Sn:Ni = 7:3 N₃Sn₄ + β-Sn 0.07 8:2 — 11 Ag:Sn = 4:6ε-Phase + β-Sn phase 0.30 Sn:Ni = 7:3 N₃Sn₄ + β-Sn 0.07 8:2 — 12 Ag:Sn =3:1 ε-Phase 0.30 Sn:Ni = 7:3 N₃Sn₄ + β-Sn 0.07 8:2 — 13 Ag:Sn = 8:2ζ-Phase + ε-phase 0.30 Sn:Ni = 4:6 Ni₃Sn₂ 0.07 8:2 — 14 Ag:Sn = 8:2ζ-Phase + ε-phase 0.30 Sn:Ni = 5:5 Ni₃Sn₂ + Ni₃Sn₄ 0.07 8:2 — 15 Ag:Sn =8:2 ζ-Phase + ε-phase 0.10 Sn:Ni = 7:3 N₃Sn₄ + β-Sn 0.20 1:2 — 16 Ag:Sn= 8:2 ζ-Phase + ε-phase 0.30 Sn:Ni = 7:3 N₃Sn₄ + β-Sn 0.07 8:2 — 17Ag:Sn = 8:2 ζ-Phase + ε-phase 0.30 Sn:Ni = 7:3 N₃Sn₄ + β-Sn 0.07 8:2 —18 Ag:Sn = 8:2 ζ-Phase + ε-phase 0.30 Sn:Ni = 7:3 N₃Sn₄ + β-Sn 0.07 8:2— 19 Ag:Sn = 8:2 ζ-Phase + ε-phase 0.30 Sn:Ni = 7:3 N₃Sn₄ + β-Sn 0.078:2 — 20 Ag:Sn = 8:2 ζ-Phase + ε-phase 0.30 Sn:Cu = 7:3 — 0.07 8:2 — 21Ag:Sn = 8:2 ζ-Phase + ε-phase 0.05 Sn:Ni = 7:3 N₃Sn₄ + β-Sn 0.25 17:83 —22 Ag:Sn = 8:2 ζ-Phase + ε-phase 0.30 Sn:Ni = 37:63 Ni₃Sn + Ni₃Sn₄ 0.078:2 — 23 Ag:Sn = 8:2 ζ-Phase + ε-phase 0.30 Sn:Ni = 55:45 Ni₃Sn₄ 0.078:2 — 24 Ag:Sn = 8:2 ζ-Phase + ε-phase 0.30 Sn:Ni = 7:3 N₃Sn₄ + β-Sn0.07 8:2 Ag:Ni = 1:4, 0.03 μm 41 Ag:Sn = 3:1 ε-Phase 0.30 Sn:Ni = 55:45Ni₃Sn₄ 0.07 8:2 — Reference 1 Ag:Sn = 3:7 ε-Phase + β-Sn phase 0.30Sn:Ni = 7:3 N₃Sn₄ + β-Sn 0.07 8:2 — Examples 2 Ag:Sn = 8:2 ζ-Phase +ε-phase 0.30 Sn:Ni = 3:7 Ni₃Sn + Ni₃Sn₄ 0.07 8:2 — 3 Ag:Sn = 8:2ζ-Phase + ε-phase 0.90 Sn:Ni = 7:3 N₃Sn₄ + β-Sn 0.07 93:7  — 4 Ag:Sn =8:2 ζ-Phase + ε-phase 0.07 Sn:Ni = 7:3 N₃Sn₄ + β-Sn 0.20 1:3 — 5 Ag:Sn =8:2 ζ-Phase + ε-phase 0.30 Sn:Ni = 7:3 N₃Sn₄ + β-Sn 0.07 8:2 — 6 Ag:Sn =8:2 ζ-Phase + ε-phase 0.05 Sn:Ni = 7:3 N₃Sn₄ + β-Sn 0.25 17:83 — 7 Ag:Sn= 8:2 ζ-Phase + ε-phase 0.05 Sn:Ni = 7:3 N₃Sn₄ + β-Sn 0.25 17:83 — 8Ag:Sn = 8:2 ζ-Phase + ε-phase 0.30 Sn:Ni = 7:3 N₃Sn₄ + β-Sn 0.07 8:2 — 9Ag:Sn = 8:2 ζ-Phase + ε-phase 0.03 Sn:Ni = 7:3 N₃Sn₄ + β-Sn 0.07 3:7 —Compar- 1 Ag:Sn = 8:2 ζ-Phase + ε-phase 0.01 Sn:Ni = 7:3 N₃Sn₄ + β-Sn0.07 13:87 — ative 2 Ag:Sn = 8:2 ζ-Phase + ε-phase 1.30 Sn:Ni = 7:3N₃Sn₄ + β-Sn 0.07  5:95 — Examples 3 Sn βSn 0.6 Sn:Ni = 7:3 N₃Sn₄ + β-Sn0.07 9:1 — 4 Ag:Sn = 8:2 ζ-Phase + ε-phase 0.90 Sn:Ni = 7:3 N₃Sn₄ + β-Sn0.005 99:1  — 5 Ag:Sn = 8:2 ζ-Phase + ε-phase 0.30 Sn:Ni = 7:3 N₃Sn₄ +β-Sn 0.50 38:62 — 6 Ag:Sn = 8:2 ζ-Phase + ε-phase 0.30 Sn:Ni = 7:3N₃Sn₄ + β-Sn 0.07 8:2 — 7 Ag:Sn = 8:2 ζ-Phase + ε-phase 0.30 Sn:Ni = 7:3N₃Sn₄ + β-Sn 0.07 8:2 — 8 Ag—Sn = 97:3 ε-Phase + β-Sn phase 0.9 — — 9Ag—Sn = 92:8 ε-Phase + β-Sn phase 0.45 — — 11 Sn 0.8 — — — — — Intended0.02 or 0.01 or target more and more and less than less than 1.00 0.40

TABLE 4 Whiskers Number of Number of Upper layer whiskers whiskers ofLower layer Surface Lower layer less than 20 20 μm or Thick-Nanoindentation roughness Vickers Nanoindentation μm in more in nesshardness Ra Rz hardness hardness length length Composition [μm] [MPa][μm] [μm] Hv [MPa] [pieces] [pieces] Examples 1 Ni (semi-glossy) 1 40000.22  2.35 300 3400 0 0 2 Ni (semi-glossy) 1 — — — — — 0 0 3 Ni(semi-glossy) 1 — — — — — 0 0 4 Ni (semi-glossy) 1 — — — — — 0 0 5 Ni(semi-glossy) 1 — — — — — 0 0 6 Ni (semi-glossy) 1 — — — — — 0 0 7 Ni(semi-glossy) 0.07 — — — — — 0 0 8 Ni (semi-glossy) 0.5 — — — — — 0 0 9Ni (semi-glossy) 3 — — — — — 0 0 10 Ni (semi-glossy) 1 — — — — — 0 0 11Ni (semi-glossy) 1 — — — — — 0 0 12 Ni (semi-glossy) 1 — — — — — 0 0 13Ni (semi-glossy) 1 — — — — — 0 0 14 Ni (semi-glossy) 1 — — — — — 0 0 15Ni (semi-glossy) 1 — — — — — 0 0 16 Ni (glossy) 1 7000 — — 600 6700 0 017 Ni (matte) 1 1200 — — 130 1300 0 0 18 Ni (semi-glossy) 1 — 0.18 1.8 —— 0 0 19 Ni (semi-glossy) 1 — 0.13 1.2 — — 0 0 20 Cu 1 — — — — — 0 0 21Ni (semi-glossy) 1 — — — — — 0 0 22 Ni (semi-glossy) 1 — — — — — 0 0 23Ni (semi-glossy) 1 — — — — — 0 0 24 Ni (semi-glossy) 1 — — — — — 0 0 41Ni (semi-glossy) 1 — — — — — 0 0 Reference 1 Ni (semi-glossy) 1 — — — —— ≤1   0 Examples 2 Ni (semi-glossy) 1 — — — — — 0 0 3 Ni (semi-glossy)1 — — — — — 0 0 4 Ni (semi-glossy) 1 — — — — — 0 0 5 Ni:P = 98:2 111000  — — 1200  12000  0 0 6 Ni (semi-glossy) 1 — — — — — 0 0 7 Ni(semi-glossy) 1 — — — — — 0 0 8 Ni (semi-glossy) 1 — — — — — 0 0 9 Ni(semi-glossy) 1 — — — — — 0 0 Comparative 1 Ni (semi-glossy) 1 — — — — —— — Examples 2 Ni (semi-glossy) 1 — — — — — — — 3 Ni (semi-glossy) 1 — —— — — — ≤2   4 Ni (semi-glossy) 1 — — — — — — — 5 Ni (semi-glossy) 1 — —— — — — — 6 Ni (semi-glossy) 0.03 — — — — — — — 7 Ni (semi-glossy) 5.5 —— — — — — — 8 Ni (matte) 0.5 — — — — — — — 9 Ni (matte) 0.5 — — — — — —— 11 Ni (matte) 1 — — — — — — ≤3   Intended 0.05 or 0 target more andless than 5.00

TABLE 5 Adhesive wear Insertion force Maximum insertion Fine sliding Gascorrosion force/maximum Heat wear Solder resistance insertion forceresistance resistance wettability Hydrogen sulfide of ComparativeContact Contact Contact Zero cross Exterior Example 10 resistanceresistance resistance time appearance after Mechanical Bending [%] [mΩ][mΩ] [mΩ] [sec] test durability processability Examples 1 70 1 to 3 1 to3 10 to 50 2 to 4 Not discolored ◯ ◯ 2 66 1 to 3 1 to 3 10 to 50 2 to 4Not discolored ◯ ◯ 3 77 1 to 3 1 to 3 10 to 50 2 to 4 Not discolored ◯ ◯4 74 1 to 3 1 to 3 10 to 50 2 to 4 Not discolored ◯ ◯ 5 66 1 to 3 1 to 310 to 50 2 to 4 Not discolored ◯ ◯ 6 63 1 to 3 1 to 3 10 to 50 2 to 4Not discolored ◯ ◯ 7 83 1 to 3 1 to 3 10 to 50 2 to 4 Not discolored ◯ ◯8 77 1 to 3 1 to 3 10 to 50 2 to 4 Not discolored ◯ ◯ 9 65 1 to 3 1 to 310 to 50 2 to 4 Not discolored ◯ ◯ 10 72 1 to 3 1 to 3 10 to 50 2 to 4Not discolored ◯ ◯ 11 65 1 to 3 1 to 3 10 to 50 2 to 4 Not discolored ◯◯ 12 67 1 to 3 1 to 3 10 to 50 2 to 4 Not discolored ◯ ◯ 13 77 1 to 3 1to 3 10 to 50 2 to 4 Not discolored ◯ ◯ 14 73 1 to 3 1 to 3 10 to 50 2to 4 Not discolored ◯ ◯ 15 70 1 to 3 1 to 3 10 to 50 2 to 4 Notdiscolored ◯ ◯ 16 65 1 to 3 1 to 3 10 to 50 1 to 3 Not discolored ◯ ◯ 1776 1 to 3 2 to 4 10 to 50 2 to 4 Not discolored ◯ ◯ 18 71 1 to 3 1 to 310 to 50 2 to 4 Not discolored ◯ ◯ 19 69 1 to 3 1 to 3 10 to 50 1 to 3Not discolored ◯ ◯ 20 72 1 to 3 1 to 3 10 to 50 2 to 4 Not discolored ◯◯ 21 69 1 to 3 1 to 3 10 to 50 2 to 4 Not discolored ◯ ◯ 22 75 1 to 3 1to 3 10 to 50 2 to 4 Not discolored ◯ ◯ 23 73 1 to 3 1 to 3 10 to 50 2to 4 Not discolored ◯ ◯ 24 70 1 to 3 1 to 3 10 to 50 1 to 4 Notdiscolored ◯ ◯ 41 65 1 to 3 1 to 3 10 to 50 2 to 4 Not discolored ◯ ◯Reference 1 65 1 to 3 1 to 3  30 to 100 2 to 4 Not discolored ◯ ◯Examples 2 80 1 to 3 1 to 3 10 to 50 2 to 4 Not discolored ◯ Δ 3 83 1 to3 1 to 3 10 to 50 2 to 4 Not discolored Δ ◯ 4 71 1 to 3 3 to 5  30 to100 3 to 5 Somewhat ◯ ◯ discolored 5 63 1 to 3 1 to 3 10 to 50 2 to 4Not discolored ◯ X 6 71 1 to 3 3 to 5 10 to 50 3 to 5 Not discolored ◯ ◯7 72 1 to 3 3 to 5 10 to 50 3 to 5 Not discolored ◯ ◯ 8 72 2 to 4 3 to 710 to 50 3 to 5 Not discolored ◯ ◯ 9 70 1 to 3 3 to 5  30 to 100 3 to 5Somewhat ◯ ◯ discolored Comparative 1 — 1 to 3 10< 100< 5< Discolored —— Examples 2 88 1 to 3 — — — — X — 3 90 1 to 3 10< 100< — — — — 4 87 1to 3 — — — — — — 5 — 1 to 3 — — — — X X 6 86 1 to 3 10< — 5< — — — 7 — 1to 3 — — — — X 8 — 1 to 3 — — — Discolored — — 9 — 1 to 3 — — —Discolored — — 11 100 1 to 3 10< 100< — — — — Intended Less than 85 10or less 10 or less 100 or less 5 or less Not discolored ◯ target

TABLE 6 Minimum Thickness ratio thick- Upper layer Intermediate layerbetween upper Lower layer ness of Thick- Thick- and Thick- upper Compo-ness Compo- ness intermediate Compo- ness layer sition Structure [μm]sition Structure [μm] layers sition [μm] [Mm] Examples 21 Ag:Sn = 8.2ζ-Phase + 0.05 Sn:Ni = 7:3 N₃Sn₄ + β- 0.25 17:83 Ni 1 0.04 ε-phase Sn(Semi- Plating of Ag at 1 A/dm² followed by plating of Sn at 1 A/dm²glossy) Reference 6 Ag:Sn = 8:2 ζ-Phase + 0.05 Sn:Ni = 7:3 N₃Sn₄ + β-0.25 17:83 Ni 1 0.02 Examples ε-phase Sn (semi- Plating of Ag at 1 A/dm²followed by plating of Sn at 4 A/dm² glossy) 7 Ag:Sn = 8:2 ζ-Phase +0.05 Sn:Ni = 7:3 N₃Sn₄ + β- 0.25 17:83 Ni 1 0.03 ε-phase Sn (semi-Plating of Ag at 4 A/dm² followed by plating of Sn at 1 A/dm² glossy)Relation between thickness of upper Maximum value of layer and maximumelevation differences value of elevation Exterior Relation betweenbetween adjacent hills and differences between appearance thickness ofupper valleys in profle of adjacent hills and after gas Heat Solderlayer and interface between upper valleys in profile of corrosionresistance wettability minimum layer and intermediate interface betweenresistance test Contact Contact Zero cross thickness of upper layerupper layer and with hydrogen resistance resistance time layer [μm]intermediate layer sulfide [mΩ] [mΩ] [sec] Examples 21 Minimum 0.018Maximum value of Not discolored 1 to 3 1 to 3 2 to 4 thickness of upperelevation differences layer ≥ thickness of between adjacent upper layer× 0.5 hills and valleys in profile of interface between upper layer andintermediate layer ≤ thickness of upper layer × 0.5 Reference 6 Minimum0.021 Maximum value of Somewhat 1 to 3 3 to 5 3 to 5 Examples thicknessof upper elevation differences discolored layer < thickness betweenadjacent of upper layer × hills and valleys in 0.5 profile of interfacebetween upper layer and intermediate layer ≤ thickness of upper layer ×0.5 7 Minimum 0.039 Maximum value of Somewhat 1 to 3 3 to 5 3 to 5thickness of upper elevation differences discolored layer ≥ thickness ofbetween adjacent upper layer × 0.5 hills and valleys in profile ofinterface between upper layer and intermediate layer > thickness ofupper layer × 0.5

TABLE 7 Surface of upper layer Region where atomic concentration (at %)Heat Solder Thickness of Sn ≥ atomic con- resis- wetta- ratio centration(at %) of tance bility Upper layer Intermediate layer between Ag andatomic concen- Contact Contact Zero Thick- Thick- upper and tration (at%) of resis- resis- cross Compo- ness Compo- ness intermediate O ≥ 10 at% tance tance time sition Structure [μm] sition Structure [μm] layers[μm] [mΩ] [mΩ] [sec] Examples 1 Ag:Sn = ζ-Phase + 0.30 Sn:Ni = N₃Sn₄ +0.07 8:2 0.0005 to 0.005 1 to 3 1 to 3 2 to 4 8:2 ε-phase 7:3 β-Sn 2Ag:Sn = ζ-Phase + 0.07 Sn:Ni = N₃Sn₄ + 0.07 5:5 0.0005 to 0.005 1 to 3 1to 3 2 to 4 8:2 ε-phase 7:3 β-Sn 3 Ag:Sn = ζ-Phase + 0.60 Sn:Ni =N₃Sn₄ + 0.07 9:1 0.0005 to 0.005 1 to 3 1 to 3 2 to 4 8:2 ε-phase 7:3β-Sn Reference 8 Ag:Sn = ζ-Phase + 0.30 Sn:Ni = N₃Sn₄ + 0.07 8:2 0.030 2to 4 3 to 7 3 to 5 Examples 8:2 ε-phase 7:3 β-Sn

TABLE 8 Adhesive wear Insertion force Maximum Whiskers insertion Numberof Number of force/maximum whiskers less whiskers of 20 insertion forceof Heat resistance than 20 μm in μm or more in Comparative ContactContact length length Example 10 resistance resistance [pieces] [pieces][%] [mΩ] [mΩ] Examples 25 0 0 63 1 to 2 1 to 2 26 0 0 67 1 to 2 1 to 227 0 0 66 1 to 2 1 to 2 28 0 0 65 1 to 2 1 to 2 29 0 0 67 1 to 2 1 to 230 0 0 64 1 to 2 1 to 2 31 0 0 63 1 to 2 1 to 2 32 0 0 65 1 to 2 1 to 233 0 0 67 1 to 2 1 to 2 34 0 0 65 1 to 2 1 to 2 35 0 0 65 1 to 2 1 to 236 0 0 67 1 to 2 1 to 2 37 0 0 65 1 to 2 1 to 2 38 0 0 64 1 to 2 1 to 239 0 0 68 1 to 2 1 to 3 40 0 0 70 1 to 3 1 to 3 Intended 0 Less than 8510 or less 10 or less target Gas corrosion Fine sliding resistance wearHydrogen resistance Solder sulfide Contact wettability Exterior Mechan-resistance Zero cross time appearance ical dura- Bending [mΩ] [sec]after test bility processability Examples 25 10 to 30 0.5 to 2 Notdiscolored ◯ ◯ 26 10 to 30 0.5 to 2 Not discolored ◯ ◯ 27 10 to 30 0.5to 2 Not discolored ◯ ◯ 28 10 to 30 0.5 to 2 Not discolored ◯ ◯ 29 10 to30 0.5 to 2 Not discolored ◯ ◯ 30 10 to 30 0.5 to 2 Not discolored ◯ ◯31 10 to 30 0.5 to 2 Not discolored ◯ ◯ 32 10 to 30 0.5 to 2 Notdiscolored ◯ ◯ 33 10 to 30 0.5 to 2 Not discolored ◯ ◯ 34 10 to 30 0.5to 2 Not discolored ◯ ◯ 35 10 to 30 0.5 to 2 Not discolored ◯ ◯ 36 10 to30 0.5 to 2 Not discolored ◯ ◯ 37 10 to 30 0.5 to 2 Not discolored ◯ ◯38 10 to 30 0.5 to 2 Not discolored ◯ ◯ 39 10 to 40   1 to 3 Notdiscolored ◯ ◯ 40 10 to 50   2 to 4 Not discolored ◯ ◯ Intended 100 orless 5 or less Not discolored ◯ ◯ target

Examples 1 to 41 were each a metallic material for electronic componentsexcellent in any of the low degree of whisker formation, the lowadhesive wear property and the high durability.

In Reference Example 1, the ratio of Ag:Sn in the upper layer was 3:7for the proportion of Sn in the upper layer to be larger as comparedwith Example 1, and hence the whiskers less than 20 μm in lengthsometimes occurred, although the intended properties were obtained andthe whiskers of 20 μm or more in length did not occur.

In Reference Example 2, the ratio of Sn:Ni in the intermediate layer was3:7, the proportion of Ni in the intermediate layer was larger ascompared with Example 1, and hence the bending processability wassomewhat poorer as compared with Example 1 although the intendedproperties were obtained.

In Reference Example 3, the thickness of the upper layer was 0.90 μm,the thickness of the upper layer was larger as compared with Example 1,and the mechanical durability was somewhat poorer as compared withExample 1 although the intended properties were obtained.

In Reference Example 4, the thickness ratio between the upper layer andthe lower layer was such that upper layer:lower layer=1:3, thus theproportion of the lower layer was larger, and hence the heat resistance,the fine sliding wear resistance, the solder wettability and the gascorrosion resistance were somewhat poorer as compared with Examplesalthough the intended properties were obtained.

In Reference Example 5, the nanoindentation hardness of the upper layer,and the nanoindentation hardness and the Vickers hardness of the lowerlayer were larger as compared with Example 1, and hence the bendingprocessability was poor although the intended properties were obtained.

In Reference Example 6, the minimum thickness of the outermost layer wasless than 50% of the thickness of the outermost layer, the heatresistance, the solder wettability and the gas corrosion resistance werepoorer than those of Examples although the intended properties wereobtained.

In Reference Example 7, the maximum value of the elevation differencesbetween the adjacent hills and valleys in the profile of the interfacebetween the outermost layer and the upper layer exceeds 50% of thethickness of the outermost layer, and hence the heat resistance, thesolder wettability and the gas corrosion resistance were poorer thanthose of Examples although the intended properties were obtained.

In Reference Example 8, on the surface of the upper layer, a regionwhere the total atomic concentration (at %) of the constituent elementsB≥the total atomic concentration (at %) of the constituent elements Cand the atomic concentration (at %) of O≥10 at % was present in therange exceeding 0.02 μm, and hence the heat resistance and the solderwettability were poorer than those of Examples although the intendedproperties were obtained.

In Reference Example 9, the thickness of the upper layer was as thinneras 0.03 μm than those of Examples, the heat resistance, the solderwettability and the gas corrosion resistance were poorer than those ofExamples although the intended properties were obtained.

In Comparative Example 1, the thickness of the upper layer was thinnerthan the intended target, and hence the heat resistance, the finesliding wear resistance, the solder wettability and the gas corrosionresistance were poor.

In Comparative Example 2, the thickness of the upper layer was thickerthan the intended target, and hence the adhesive wear was large andaccordingly the insertion force was high, and the mechanical wear waspoor.

In Comparative Example 3, β-Sn was alone present in the upper layer, andhence whiskers of 20 μm or more in length occurred, the adhesive wearwas large, accordingly the insertion force was high, and the heatresistance and the fine sliding wear resistance were poor.

In Comparative Example 4, the thickness of the intermediate layer wasthinner than the intended target, and hence the adhesive wear was largeand accordingly the insertion force was high.

In Comparative Example 5, the thickness of the intermediate layer wasthicker than the intended target, and hence the mechanical wear and thebending processability were poor.

In Comparative Example 6, the thickness of the lower layer was thinnerthan the intended target, and hence the adhesive wear was large andaccordingly the insertion force was high, and the heat resistance andthe solder wettability were poor.

In Comparative Example 7, the thickness of the lower layer was thickerthan the intended target, and hence the bending processability was poor.

In each of Comparative Examples 8 to 9, the proportion of Ag in theupper layer was high, and hence the gas corrosion resistance was poor.

Comparative Example 11 is the blank material of the present invention.In Comparative Example 11, the whiskers of 20 μm or more occurred, andthe heat resistance and the fine sliding wear resistance were poor.

FIG. 5 shows the results of the line analysis with a STEM (scanningtransmission electron microscope) according to an embodiment of thepresent invention. As can be seen from FIG. 5, sequentially from theoutermost surface, an Ag—Sn alloy was present in a thickness of 0.3 μm,and an Sn—Ni alloy was present in a thickness of 0.07 μm. Moreover, thecomposition (at %) of the Ag—Sn alloy is such that Ag:Sn=8:2, and as canbe seen from the Ag—Sn phase diagram of FIG. 6, β-Sn is not present inthe Ag—Sn alloy, and the ζ-phase (Sn: 11.8 to 22.9%) and the ε-phase(Ag₃Sn) of the Sn—Ag alloy are present. The composition (at %) of theSn—Ni alloy is such that Sn:Ni=7:3, and as can be seen from the Sn—Niphase diagram of FIG. 7, Ni₃Sn₄ of the Sn—Ni alloy and β-Sn are present.

REFERENCE SIGNS LIST

-   10 Metallic material for electronic components-   11 Base material-   12 Lower layer-   13 Intermediate layer-   14 Upper layer

The invention claimed is:
 1. A metallic material for electroniccomponents, comprising: a base material; a lower layer formed on thebase material, the lower layer comprising one or two or more selectedfrom a constituent element group A consisting of Ni, Cr, Mn, Fe, Co andCu; an intermediate layer formed on the lower layer, the intermediatelayer consisting of one or two or more selected from the constituentelement group A and one or two selected from a constituent element groupB consisting of Sn and In; and an upper layer formed on the intermediatelayer, the upper layer comprising an alloy composed of one or twoselected from the constituent element group B and one or two or moreselected from a constituent element group C consisting of Ag, Au, Pt,Ru, Rh, Os and Ir, wherein the thickness of the lower layer is 0.05 μmor more and less than 5.00 μm; the thickness of the intermediate layeris 0.01 μm or more and less than 0.40 μm; and the thickness of the upperlayer is 0.02 μm or more and less than 1.00 μm, and the upper layercomprises the metal(s) of the constituent element group B in a contentof 10 to 50 at %, the minimum thickness (μm) of the upper layer is 50%or more of the thickness (μm) of the upper layer, and the maximum value(μm) of the elevation differences between the adjacent hills and valleysin the profile of the interface between the upper layer and theintermediate layer is 50% or less of the thickness (μm) of the upperlayer.
 2. The metallic material for electronic components according toclaim 1, wherein on the surface of the upper layer, a region where thetotal atomic concentration (at %) of the constituent elements of groupB≥ the total atomic concentration (at %) of the constituent elements ofgroup C and the atomic concentration of O≥10 at % is present in theregion of 0.02 μm or less in depth from the surface.
 3. The metallicmaterial for electronic components according to claim 1, wherein aζ(zeta)-phase being a Sn—Ag alloy and/or an ε(epsilon)-phase being aSn—Ag alloy is present.
 4. The metallic material for electroniccomponents according to claim 3, wherein β-Sn being a Sn single phase isfurther present.
 5. The metallic material for electronic componentsaccording to claim 1, wherein the intermediate layer includes a metal(s)of the constituent element group B in a content of 35 at % or more. 6.The metallic material for electronic components according to claim 1,wherein in the intermediate layer, Ni₃Sn₄ and Ni₃Sn₂ are present.
 7. Themetallic material for electronic components according to claim 1,wherein in the intermediate layer, Ni₃Sn₄ and β Sn being a Sn singlephase are present.
 8. The metallic material for electronic componentsaccording to claim 1, wherein the thickness ratio between the upperlayer and the intermediate layer is such that the upper layer: theintermediate layer =9:1 to 3:7.
 9. The metallic material for electroniccomponents according to claim 1, wherein in the range from the upperlayer to the intermediate layer, exclusive of the range of 0.03 μm fromthe outermost surface of the upper layer, C, S and O are each includedin a content of 2 at % or less.
 10. The metallic material for electroniccomponents according to claim 1, wherein the indentation hardness of thesurface of the upper layer, being the hardness obtained by ananoindentation hardness test indenting the surface of the upper layerwith a load of 10 mN, is 1000 MPa or more.
 11. The metallic material forelectronic components according to claim 1, wherein the indentationhardness measured from the surface of the upper layer, being thehardness obtained by a nanoindentation hardness test indenting thesurface of the upper layer with a load of 10 mN, is 10000 MPa or less.12. The metallic material for electronic components according to claim1, wherein in the lower layer the content of the metal(s) of theconstituent element group A is 50% by mass or more in terms of the totalcontent of Ni, Cr, Mn, Fe, Co and Cu, and one or two or more selectedfrom the group consisting of B, P, Sn and Zn are further included. 13.The metallic material for electronic components according to claim 1,wherein the indentation hardness of the cross section of the lowerlayer, being the hardness obtained by a nanoindentation hardness testindenting the cross section of the lower layer with a load of 10 mN is10000 MPa or less.
 14. The metallic material for electronic componentsaccording to claim 1, wherein the intermediate layer comprises Ni₃Sn andNi₃Sn₂.
 15. The metallic material for electronic components according toclaim 1, wherein the intermediate layer comprises Ni₃Sn₂.
 16. Themetallic material for electronic components according to claim 1,wherein the intermediate layer comprises Ni₃Sn₄.
 17. The metallicmaterial for electronic components according to claim 1, furthercomprising, between the lower layer and the intermediate layer, a layercomprising the alloy of the metal(s) of the constituent element group Aand the metal(s) of the constituent element group C.
 18. The metallicmaterial for electronic components according to claim 1, wherein P isdeposited on the surface of the upper layer, and the deposition amountof P is 1×10⁻¹¹ to 4×10⁻⁸ mol/cm².
 19. The metallic material forelectronic components according to claim 18, wherein in an XPS analysisperformed for the upper layer, with l(P2s) denoting the photoelectrondetection intensity due to the 2S orbital electron of P to be detectedand l(N1s) denoting the photoelectron detection intensity due to the 1Sorbital electron of N to be detected, the relation 0.1≤I(P2s)/I(N1s)≤1is satisfied.
 20. The metallic material for electronic componentsaccording to claim 18, wherein in an XPS analysis performed for theupper layer, with I(P2s) denoting a photoelectron detection intensitydue to a 2S orbital electron of P to be detected and I(N1s) denoting aphotoelectron detection intensity due to a 1S orbital electron of N tobe detected, the relation 1≤I(P2s)/I(N1s) ≤50 is satisfied.
 21. A methodfor producing the metallic material for electronic components accordingto claim 18, the metallic material comprising: a base material; a lowerlayer formed on the base material, the lower layer comprising one or twoor more selected from a constituent element group A consisting of Ni,Cr, Mn, Fe, Co and Cu; an intermediate layer formed on the lower layer,the intermediate layer consisting of one or two or more selected fromthe constituent element group A and one or two selected from aconstituent element group B consisting of Sn and In; and an upper layerformed on the intermediate layer, the upper layer comprising an alloycomposed of one or two selected from the constituent element group B andone or two or more selected from a constituent element group Cconsisting of Ag, Au, Pt, Ru, Rh, Os and Ir, and the upper layercomprises the metal(s) of the constituent element group B in a contentof 10 to 50 at %, the minimum thickness (μm) of the upper layer is 50%or more of the thickness (μm) of the upper layer, and the maximum value(μm) of the elevation differences between the adjacent hills and valleysin the profile of the interface between the upper layer and theintermediate layer is 50% or less of the thickness (μm) of the upperlayer; wherein the surface of the metallic material is surface-treatedwith a phosphoric acid ester-based solution including at least one ofthe phosphoric acid esters represented by the following formulas 1 and2, and at least one selected from the group of the cyclic organiccompounds represented by the following general formulas 3a, 3b, 3c, 3d,3e, 3f, 3g, 3h, 3i, and 3j, and the formulas 4a, 4b, and 4c:

wherein, in formulas 1 and 2, R₁ and R₂ each represent a substitutedalkyl group and M represents a hydrogen atom or an alkali metal atom;

wherein, in formula 4a, R₁ represents a hydrogen atom, an alkyl group ora substituted alkyl group; R₂ represents an alkali metal atom, ahydrogen atom, an alkyl group or a substituted alkyl group; in formula4c, R₃ represents an alkali metal atom or a hydrogen atom; in formula 4bR₄ represents —SH, an alkyl group-substituted or aryl group-substitutedamino group, or represents an alkyl-substituted imidazolylalkyl group;and R₅ and R₆ each represent —NH₂, —SH or —SM, wherein M represents analkali metal atom.
 22. The method for producing a metallic material forelectronic components according to claim 21, wherein the surfacetreatment with the phosphoric acid ester-based solution is performed byapplying the phosphoric acid ester-based solution to the upper layer.23. The method for producing a metallic material for electroniccomponents according to claim 21, wherein the surface treatment with thephosphoric acid ester-based solution is performed by conducting anelectrolysis by immersing the metallic material after the formation ofthe upper layer in the phosphoric acid ester-based solution and using asthe anode the metallic material after the formation of the upper layer.24. A connector including a contact portion, using, in the contactportion thereof, the metallic material for electronic componentsaccording to claim
 1. 25. An FFC terminal including a contact portion,using, in the contact portion thereof, the metallic material forelectronic components according to claim
 1. 26. An FPC terminalincluding a contact portion, using, in the contact portion thereof, themetallic material for electronic components according to claim
 1. 27. Anelectronic component including an electrode for external connection andusing, in the electrode thereof for external connection, the metallicmaterial for electronic components according to claim
 1. 28. Anelectronic component using the metallic material for electroniccomponents according to claim 1, having a mounting portion to beattached to a housing wherein a female terminal connection portion and aboard connection portion are provided respectively on one side and theother side of the mounting portion in a push-in type terminal thereoffor fixing the board connection portion to a board by pushing the boardconnection portion into a through hole formed in the board.